1. Terraqua Columns - Logistics

Time
30 min ecosystem lesson and discussion
20 min build terraqua column frame
20 min add soil, water, and seeds
* I recommend building the terraqua column frame on one day then adding the soil, water, and seeds the following day.

Grouping
2-3 students

Materials
For each group:

• 1 clear 2 Liter soda bottles
• 1 foot wick (1-2 cm wide strip of old cotton towel)

For 2-3 groups to share:

• Awl OR electric drill with 3/8 inch bit
• Hole punch
• Box cutter
• Scissors
• Sharpie marker

For whole class to share:

• Soil, either store-bought potting soil or soil from outside
• Hand trowel
• 1 package radish seeds OR Wisconsin Fast Plant seeds
• Water, either tap water or pond/creek water
• Graduated cylinder

Optional:

• Rubbing alcohol (for erasing sharpie marker lines)
• Clear tape

Setting
Classroom

1. Terraqua Columns - Background

Teacher Background
Understanding ecosystems is the basis for all of the study of ecology. Students are introduced to the idea of an ecosystem by examining his or her interactions with other living things and the environment. The terraqua column that students build becomes the foundation for the following weeks of exploration of water, soil, living things, and the environment.

Bottle Biology contains a wealth of information about the terraqua column project and further directions to explore. Definitely check out the Bottle Basics section to learn about working with soda bottles and also the Terra Column section for everything you wanted to know about building, maintaining, and studying terraqua columns. This site has a much more detailed step-by-step building guide complete with diagrams and troubleshooting.

Student Prerequisites
none

1. Terraqua Columns - Getting Ready

Getting Ready

1. Build your own terraqua column as an example to show the students.
2. You may want to pre-drill the holes in the bottle caps.
3. Place bottles and wicks in an easily accessible place in the classroom.
4. Create terraqua column building kits with the awl or electric drill, hole punch, box cutter, scissors, and sharpie markers for a few groups of students to share.
5. You may want to print out a copy of the building instructions as an overhead or make enough copies for each group to have one.
6. Create a planting area with the soil, trowel, and seeds.
7. Place graduated cylinders near the sink or water source.
   

1. Terraqua Columns - Lesson Plan

Ecosystem lesson and discussion

1. On a blank sheet of paper, ask each student to draw a small stick figure in the middle of the page to represent him/herself.
2. Instruct students to write down as many living (or formerly living) things that you interact with in your daily life in the space around the stick figure. Connect each thing to the stick figure with a line. You may want to start an example on the board for students to build from. Think about family, friends, teachers, other people, pets, food, plants, garbage, etc. Give students at least 5 minutes to create a diagram.
3. Around the diagram, draw or describe the environment in which these interactions take place. You may want to add to the example on the board. Think about home, school, the outdoors, the city, the neighborhood, etc.
4. Spend 10-15 minutes discussing and sharing the diagrams that students created. Focus on the interactions between a student and the other organisms and on the interaction between a student and his/her environment. You may want to introduce the term "organism" as a living thing. Some questions to encourage discussion:
   • How many interactions did you come up with? Are there more?
   • What interactions did everyone have in common?
   • What interactions did only some people have?
   • What kind of interactions do you have with living things? With non-living things?
   • Can we group interactions together into categories?
5. Tell students that their diagrams illustrate their personal ecosystem. Encourage students to help come up with a definition of an ecosystem. Ecosystem - a group of organisms that interact among themselves and with the environment in which they live
6. Describe other ecosystems (a forest, a meadow, a mountain) and the interactions that occur between organisms and between organisms and their environment. Consider both small (a fish tank) and large (planet Earth) ecosystems.
7. Conclude the discussion with the question: Are we all part of the same ecosystem? Is someone in Asia part of our ecosystem?

Terraqua column construction

1. Explain that students will be building mini-ecosystems called terraqua columns. Give students an overview of what they will be doing with their terraqua columns over the next 2-3 weeks.
2. Divide students into groups of 2 or 3 students. Once students are seated with their group, distribute 1 soda bottle and wick to each group. Distribute terraqua column building kits around the classroom so that materials can easily be shared.
3. Remove the label from your soda bottle.
4. With a Sharpie marker, draw a line around the bottle 2 cm below the shoulder curve (where the bottle curves towards the opening). You will want to visually make sure that the students drew their lines in the right place.
5. Use the box cutter to poke a slit along the line.
6. Use scissors to cut the rest of the way around the line. The larger, bottom part of the bottle is your "reservoir". The smaller, upper part of the the bottle is your "planter".
7. Use the hole puncher to punch 2-3 holes near the upper rim of the reservoir. The holes allow air to circulate in the water portion of the terraqua column. This is not as necessary if you intend to use tap water.
8. Poke a 1 cm hole in the cap with an awl or drill a 3/8 inch hole with an electric drill. To save time or improve classroom management, this can be done ahead of time by the teacher.
9. Use a Sharpie to label the reservoir with the names of the group members.

Filling the Terraqua Column

1. Saturate the wick in water.
2. Insert the wick through the hole in the cap. Screw the cap onto the opening of the bottle.
3. Invert the planter onto the reservoir. Make sure that the wick reaches all the way from the bottom of the reservoir to the top of the planter.
4. Add water to the reservoir. I found that 500 mls was a good amount of water. If you want students to monitor the water level and learn about measurement, you can add water to the reservoir in 100 ml units and mark the side of the reservoir with a sharpie at the top of the water line.
5. Add soil to the planter. When adding the soil, hold the end of the wick up and fill in the soil around the wick. Make sure that the wick is not stuck against the side of the planter. Bury the top of the wick in the soil.
6. Plant 5 seeds in the soil.
7. Water the soil with 100 mls of water.
8. Have students make initial observations of their terraqua columns. You may want to record:
   • Amount and type of water added
   • Number, type, and location of seeds planted
   • Type of soil added
   • Color and texture of soil
   • Color of water
9. You may want to tape the planter and reservoir together with clear tape.

1. Terraqua Columns - Assessments

Assessment
Create an ecosystem diagram for an animal of your choice. Be sure to include interactions between your animal and other organisms AND between your animal and its environment.

Going Further

1. Conduct soil analysis on the planter part of the terraqua column. See Soil Analysis lesson.
2. Conduct water quality assessment on the reservoir part of the terraqua column. See Water Quality lesson.
3. Conduct an independent investigation using terraqua columns. See Terraqua Column Experiment lesson.
4. Study the life cycle of plants from seed to germination to maturity and flowering to the production of new seeds. Use Wisconsin Fast Plants as part of the Raising Plants lesson.

1. Terraqua Columns - Sources and Standards

Sources
Bottle Biology contains everything you wanted to know about terraqua columns.

The Learner website has wonderful pictures of terraqua columns in progress as well as many extensions to try.

Standards
Grade Six
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment.

2. Water Analysis - Logistics

Time
5 min introduction to water quality 20-25 min conduct water quality tests 20-30 min discussion of class results

Grouping
2-3 students

Materials
For whole class to share:

• 1 package removable dot labels or rolls of masking tape
• pH test strips
• dissolved oxygen test kit - Kits cost between $10-60 depending on the type of test. Usually, each kit can perform 50-100 tests. They are widely available at pet stores (for testing fish tanks) and at science supply stores. See the Sources section for a selection of distributors.
• 4 pool or aquarium thermometers
• a stack of disposable paper cups (the 5 ox Dixie cups available for $3 at supermarkets and pharmacies work well)
• various water sources to compare against room temperature tap water
  • for the temperature test try water in the sun, ice water, water on black asphalt, water in the shade, etc.
  • for the pH test try rainwater, vinegar, muddy water, stream water, bottled water, soda, diluted detergent, fertilizer, fish tank water, salt water, etc.
  • for the dissolved oxygen test try water left in the refrigerator overnight, boiled water, water bubbled with an aquarium pump, fish tank water, etc.

Setting
Classroom, although some tests such as water left out on black asphalt might require access to the outdoors.

2. Water Analysis - Background

Teacher Background
This activity, like the Soil Analysis activity are fabulous springboards for future independent investigations and real world connections. Water quality is one of the first things analyzed by environmentalists, government agencies, aquarium owners, gardeners, and business men and women when asked about the health of an ecosystem. It is a question you can ask about the water that comes out of your tap and that goes down the drain. This lesson gives students experience with 3 very simple water quality measures although there are many many more tests available to try (salinity, phosphates, chlorine, nitrates, fecal coliform, and others).

The first test is temperature which simply measures how hot or cold something is. Water temperature significantly affects the type of life that can survive. High temperatures reduce the amount of dissolved oxygen. The rate of photosynthesis gradually increases as water temperature rises, although beyond 32 degrees Celcius, the rate of photosynthesis falls again. Similarly the metabolic rate of plankton, insects, and other water life varies according to the temperature of the water. Human impacts that can affect water temperature include thermal pollution from industry, deforestation resulting in fewer trees to shade water, and soil erosion adds sediments to the water increasing the absorption of solar heat.

The second test measures pH. pH is a measure of the hydrogen ion concentration in liquids and other substances. Acids such as vinegar and lemon juice have high concentrations of hydrogen ions and register below 7 on the pH scale. Bases such as soap and milk have low concentrations of hydrogen ions and register above 7 on the pH scale. Pure deionized water has a neutral value of 7. Pure rainwater has a pH closer to 5.6 although natural freshwater sources such as creeks, ponds, and lakes fall between 6.5 and 8.5. Some water sources such as bogs (with a pH as low as 4.2) have naturally low pH. Human impacts such as acid rain, pollution, and chemical spills can affect pH values.

The final test, dissolved oxygen, measures the presence of oxygen in the water, an essential ingredient for animal life. Dissolved oxygen is measured in parts per million or ppm. Although some organisms can survive at very low dissolved oxygen levels, 7-14 ppm is generally considered healthy for most fish and other aquatic life. Levels of 3-5 ppm are considered stressful and 0 is termed anoxic. Oxygen is introduced into water from the atmosphere (running water and wind increases the amount of oxygen) and from aquatic plants. A reduction in dissolved oxygen often is the result of increased temperature, changes in stream flow such as damming a river, the build up of organic wastes from pesticides and fertilizers, and eutrophication (if too much algae and plant life grows, as the plants die the bacteria population explodes, virtually eliminating all dissolved oxygen from the area).

Student Prerequisites
none

2. Water Analysis - Getting Ready

Getting Ready

1. Prepare 3 stations around the classroom with the materials needed to conduct that test and a printout of the student instructions (see attachment at bottom of summary page).
   1. Temperature: thermometers, water samples
   2. pH: pH paper, labels, small cups, water samples
   3. dissolved oxygen: dissolved oxygen kit (the student instructions are written for the tablet based test from Acorn Naturalist), labels, water samples

2. Water Analysis - Lesson Plan

Lesson Plan

1. Introduce students to the idea of water quality testing. Water testing allows students to get a snapshot of the health of a body of water. Today's lesson is an opportunity to learn how to conduct these tests and interpret their results. These skills will be used later on in the course to examine water samples from terraqua columns and/or local water sources.
2. Introduce each of the 3 tests and give a description of what each test measures and how each test is performed. You may want to quickly demonstrate each test using tap water as an example as you explain the procedure. Ask students for predictions of what differences one might expect between water samples?
3. Specify the organization of the student's lab notebook and decide how data should be recorded at each station.
4. Divide the students into groups and specify the rotation strategy. Rotate through the 3 stations, giving students 5-10 minutes per station. Allow time for a thorough clean up at the end of each station.
5. Engage the students in a discussion of the differences between the water samples at each station. One way to do this would be to create a summary of all the students' results from each test on the board or on an overhead. Students can offer observations and comparisons for each test to add to the summarized results at the front of the room. Some examples of questions to ask:
   
   1. Were you surprised by any of the results?
   2. What do differences in temperature mean?
   3. What natural and man-made events might cause differences in temperature at a creek or lake? (depth, shade, velocity, altitude)
   4. What do differences in pH mean?
   5. What might cause pH differences?
   6. How should we interpret differences in dissolved oxygen?
   7. What conditions would increase or decrease dissolved oxygen?
   8. Would plant life increase or decrease dissolved oxygen? How about rotting plant life?
   9. How would differences in temperature/pH/dissolved oxygen affect the types of plants or animals that could survive in that water?
   10. How do different variables affect one another? For instance, how does temperature relate to dissolved oxygen?
   11. Did everyone get the same results? Why or why not?
6. Armed with a thorough analysis of these water samples, begin a discussion of what makes water "healthy". Challenge students to decide what ranges of values for the various tests would be "healthiest"? and what range of values would be "unhealthy"?. This question is very open-ended and does not have a right or wrong answer but is an excellent way to generate discussion and delve deeply into the issue of water quality. One way to conduct this discussion is to allow students time to speak with their group about the question first, then share the group's conclusion with the rest of the class. A key factor to bring up is whether "healthy"? water is the same regardless of its location or use (such as a creek, pond, lake, bay or ocean).
7. An alternative to the discussion of healthy water is to discuss the human activities that can affect water quality, both in good and bad ways. Challenge students to come up with a human impact (for example, pollution) and think about how that impact would change temperature, pH, and dissolved oxygen. Some possible impacts to consider include:
   • Pollution
   • Acid rain
   • Deforestation
   • Invasive species such as elodea (commonly found in fish tanks but which can rapidly cover the entire surface of a pond)
   • Dams
   • Wastewater treatment
   • Planting trees
   • Fishing and recreation

2. Water Analysis - Assessments

Assessment

1. Describe one thing that humans do that changes water quality - either making it worse or better. How would it affect each of the 3 tests we conducted during class?
2. Research another water quality test. What does that test measure? How do you perform that test? What are the natural readings and what are unnatural readings? Describe 2 natural reasons why readings would vary. Describe 2 human impacts that could affect the test.

Going Further

1. Conduct water quality analysis on the reservoir part of the terraqua column. See Terraqua Column lesson.
2. Conduct water quality analysis at the creek restoration site before and after restoration.See Habitat Survey lesson
3. Conduct an independent investigation using terraqua columns that monitors water quality. See Terraqua Column Experiment lesson.

2. Water Analysis - Sources and Standards

Sources
Distributors of water quality test kits:

• Red Sea makes the least expensive dissolved oxygen test kit I have found with 60 tests for $10. It is available at many pet stores or you can order it online at A Fishy Business. Some of the ingredients are toxic so use all available safety precautions with kids - gloves, aprons, eye protection, etc.
• In my own classes I used a test kit from Acorn Naturalists 100 tests for $25. It is very simple for students to use - just add 2 pellets, shake and wait for a color change - however it only gives 3 readout levels: anoxic, poor and good. In fact, I could not get water bubbled overnight with an aquarium pump bubbler to give me a good readout.
• I'm tempted to try Chemetrics next year to obtain more accurate readings. It is more expensive at 30 tests for $40.
• Other sources of water quality test kits include:
  • Proaquatica
  • LaMotte Company
  • Hach Company
  • Carolina Biological

This activity was adapted from Monitoring Creek Health a 6-8th grade curriculum written by the Point Reyes National Seashore Association. Save the Bay also developed a superb curriculum which includes many ideas for mapping, monitoring, and restoring local watersheds. This lesson is in many ways modeled after Save the Bay's lesson plan “Keeping an Eye on Our Creeks". Kids in Creeks is a curriculum guide produced by the Watershed Project and is available to teachers who take their superb workshops. They provide extensive resources for teachers interested in adopting a local creek. Included in their curriculum are many water quality monitoring activites, including conducting an insect survey and a plant life survey as indicators of creek health. North Carolina State University has an excellent set of additional activities to further investigate the effects of water quality factors.

Standards
Grade 6 Ecology (Life Science)
e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.

Grade 8
Reactions
5. Chemical reactions are processes in which atoms are rearranged into different combinations of molecules. As a basis for understanding this concept:
e. Students know how to determine whether a solution is acidic, basic, or neutral.

All grades Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations.

3. Soil Analysis - Logistics

Time

Day 1: Optional: 5 min discuss soil observation homework from last night 10 min observe samples of different soil ingredients 30-40 min conduct soil quality tests

Day 2 (several days later): 15 min complete observations of Tullgren Funnel and soil separation tests 30 min discuss results and draw conclusions about "healthy" versus "unhealthy" soil

* Since the Tullgren Funnel and soil separation tests take several days, it is recommended to start Day 1 on a Friday and complete Day 2 on a Monday. *

Grouping
2-3 students

Materials
For each group of students:

• 4 petri dishes
• 2 funnels (card stock paper rolled and taped into a funnel shape and cut to 4-6 inches tall may be substituted)
• 2 funnel holders to hold funnels upright above a Petri dish (card stock paper rolled into a tube works well or you can eliminate the Petri dish as well by using a cup that the body of the funnel rests in as long as the bottom tip of the funnel does not touch the bottom of the cup)
• 2 square of cheesecloth
• 2 strips pH paper
• 2 white paper towels
• 2 clear 15 ml tubes with lids, glass or plastic

For whole class to share:

• Clay in ziplock bag
• Sand in ziplock bag
• Silt in ziplock bag
• Compost in ziplock bag
• 8 large plastic cups
• 8 plastic spoons
• 2 graduated cylinders
• 2 tablespoons
• 2 rulers
• 2 different types of soil (The more different the texture, composition, and organism content of the 2 soils, the better. For example, try soil from the school yard vs. store-bought potting soil, a clay soil vs. a sandy soil, or rich garden soil vs. soil from an abandoned lot.)
• 3-4 bare light blubs hung or mounted approximately 1 foot from the table top (desk lamps work well)
• 1 small jar alum (available at supermarkets for pickling)
• 2 magnifying glasses
• 1 package removable dot labels or rolls of masking tape

Setting
classroom

3. Soil Analysis - Background

Teacher Background
In an ecosystem, the soil and water form the foundation of the surrounding environment. Environmental impacts such as deforestation, the introduction of invasive species, climate change, acid rain and others all have profound implications on the soil and water in the area. Many changes can be readily detected and tracked by very simple tests that students can conduct with very simple materials. This lesson and the parallel water quality analysis lesson are opportunities to teach students the observational and analytical skills needed to apply these tests to real ecosystems in the real world.

The first test is a simple soil observation using all your senses. This allows students to practice observation and recording skills and helps kids notice that all soil is not the same.

The second test is a soil separation test to determine the relative proportion of clay, silt, sand and organic material. It draws on the principle of a density column where the largest, most dense particles (in this case sand) settle first. During the introduction of this portion of the activity, you can discuss density or not, depending on the background of your students. Students generally intuitively understand that in water, big heavy things will sink first. Clay soils tend to be sticky when wet and will hold together in a ball. When dry, clay soils harden to an almost rock-like density, holding very little air, thus making it difficult for critters to survive. Sandy soils tend to drain water rapidly. From a gardener's perspective, the ideal soil is a balanced mixture of sand, silt and clay with lots of air, water and organic material mixed in. The alum used during this test helps separate the particles of soil. Alum is relatively non-toxic but students should be warned not to put it in their mouths and should wash their hands after this station (and at the end of the period).

The third test measures the pH of the soil. pH is a measure of the chemical and mineral content of soil. Most plants prefer soil that is slightly acidic (between 5.5-7). However, some plants require very acidic soils (less than 4.5) to survive (such as blueberries and azaleas). Impurities and pollutants such as detergents, acid rain, and trash will alter the pH of soil. Major human disruption from mining, logging, and construction also changes the pH of soil by allowing the more neutral topsoil to erode, exposing the subsoil layers which tend to be more acidic.

The final test uses a Tullgren funnel (sometimes called a Berlese separator) to isolate bugs, worms and other critters from the soil. The basic principle is that the soil is placed in a funnel beneath a heat source. The mites, worms, and insects in the soil move downward through the soil to escape the heat and eventually fall out the bottom of the funnel into water. It can be absolutely fascinating for students to discover that soil is alive with critters large and small. Because it takes some time for the critters to fall through the funnel, (between 2-4 days) it is often ideal to allow the test to continue over a weekend. But make sure that there is enough water is the Petri dishes or the cup so that the water below the funnel does not dry out. For additional information and ideas about the Tullgren Funnel, see: The Open Door Website. How do you identify the critters? Great question and as of now, I have no idea. I have not found a good field guide which can be used to identify soil critters. If you find something, let us know!

Additional tests may be used or substituted for the 4 included here. For instance, you can measure the water-holding capacity of soil by adding fixed quantities of water (10 mls at a time for instance) to fixed quantities of dry soil in a funnel until water begins to drain out of the bottom. Water will continue to drain out the bottom until the soil reaches a steady state. Take the amount of water you added initially and subtract the amount of water that drained out and you have your water-holding capacity. This measurement relates closely to the composition of the soil. The more clay, the more water the soil holds. The more sand and gravel, the less water the soil holds.

What makes up healthy soil? In general, a balance of all soil ingredients with few pollutants and lots of organic material and living things makes healthy soil. Soil that completely lacks organic material or that is far outside the normal pH range is generally considered unhealthy. Soil that is completely dry cannot support life. A large number of soil critters is often a good indicator of healthy soil. However, this depends dramatically on the location and use of the soil. Soil in a garden will be different from forest soil which will be different from creek soil. Therefore, in the discussion of what makes healthy soil, expect and encourage differences in opinion.

Student Prerequisites
It is recommended that students are familiar with pH - both understanding what pH is a measure of relative to household items and how to measure it using indicators. The previous lesson 2. Water Analysis provides a sufficient introduction to those ideas.

Optional: Comparing Soil Homework - This assignment asks students to observe and compare 2 samples of soil, one from home, one from school, and to devise original tests to look for differences between the soils.

3. Soil Analysis - Getting Ready

Getting Ready

1. Prepare 4 stations around the classroom with the materials needed to conduct that test and a printout of the instructions (attachments can be found on the bottom of the summary page).
   1. Soil observation: paper towels, magnifying glass, 2 different soils labeled in plastic cups, spoons
   2. pH: petri dishes, pH paper, labels, graduated cylinders, 2 different soils labeled in plastic cups, tablespoons
   3. Soil separation: 15 ml tubes, alum, ruler, labels, 2 different soils labeled in plastic cups, spoons
   4. Tullgren Funnel: lightbulbs, funnels, cheesecloth squares, funnel holder, petridishes or cups, labels, 2 different soils labeled in plastic cups, spoons
2. Set up an example of a Soil separation test and a Tullgren funnel test at each of those stations.

3. Soil Analysis - Lesson Plan

Lesson Plan

1. Discuss the Comparing Soil Homework from the night before. This assignment asks students to observe and compare 2 samples of soil, one from home, one from school, and to devise original tests to look for differences between the soils. Some examples of questions to ask:

   • What did you observe about the school soil? about your home soil?
   • What was similar? What was different?
   • What ingredients make up soil?
   • What test did you try?
   • What did you discover?
   • What other tests could we use?

2. Show and pass around the ziplock bags of clay, silt and sand. Allow students to make comparisons between the different materials and lead them to the conclusion that clay, silt and sand are all made of rock that has been ground down to different sizes, clay being the smallest, sand being the largest. Begin a list of soil "ingredients" on the board.
3. Pass around the ziplock bag of compost. Discuss what compost is (dead, decaying organic material) and where it comes from. Discuss whether compost is good or bad for soil and consider the reasons why.
4. Ask the students what other ingredients are in soil and complete the list on the board. The major other components include water, air, living things, and minerals.
5. Optional: Discuss whether all soils have all ingredients and what the effect of missing ingredients might be.
6. Introduce today's lab and offer a brief explanation of the 4 stations students will rotate through. Ask the question why are we comparing soils and what would we want to discover?
7. Specify the organization of the student's lab notebook and decide how data should be recorded at each station.
8. Divide the students into groups and specify the rotation strategy. Rotate through the 4 stations, giving students 5-10 minutes per station. Allow time for a thorough clean up at the end of each station.
9. 2-4 days later, give students 5-10 minutes to check back on their soil separation and Tullgren Funnel tests and record their results.
10. Engage the students in a discussion of the differences between the 2 soils. One way to do this would be to create a table at the front of the classroom with columns for each of the 2 soils and rows for each of the 4 tests. Students can offer observations and comparisons for each test to add to the summarized results at the front of the room. Some examples of questions to ask:

    • Were you surprised by any of the results?
    • What do differences in pH mean?
    • What might cause pH differences?
    • How should we interpret differences in the relative amounts of clay, silt and sand?
    • Was any layer missing?
    • How would differences in soil composition affect the types of plants or animals that could live in that soil?
    • Does knowing where the 2 soils came from help explain any of the results?
    • Did everyone get the same results? Why or why not?

11. Armed with a thorough analysis of these 2 soils, begin a discussion of what makes soil "healthy". Challenge students to decide which of the 2 soils is "healthiest". This question is very open-ended and does not have a right or wrong answer but is an excellent way to generate discussion and delve deeply into the issue of soil quality. One way to conduct this discussion is to allow students time to speak with their group about the question first, then share the group's conclusion with the rest of the class. A key factor to bring up is whether "healthy" soil is the same regardless of its location or use (such as a garden, schoolyard, desert, forest or creek).

3. Soil Analysis - Assessments

Assessment

1. Soil Analysis homework (downloadable below). In this assignment, students review the soil analysis test, the major ingredients in soil, and think about why soil is important to an ecosystem.
2. Describe one thing that humans do that changes the health of the soil - either making it worse or better. How would it affect each of the 4 tests we conducted during class?

Going Further

1. Conduct soil analysis on the planter part of the terraqua column. See Terraqua Column lesson.
2. Conduct soil analysis at the creek restoration site before and after restoration. A structured way of conducting this lesson is available as part of the Habitat Survey lesson later in this unit.
3. Conduct an independent investigation using terraqua columns that monitors soil quality. See Terraqua Column Experiment project.
4. Continue the study of sediments, first through studying erosion patterns in a classroom model (see the Erosion Patterns lesson) and then through the study of sediments collected from different sites along a local creek (see Sediment Study Project).

3. Soil Analysis - Sources and Standards

Sources
Terrarium Habitats a GEMS guide by the Lawrence Hall of Science includes a great soil observation activity, including the soil separation test and Tullgren Funnel test.

The Open Door Website describes the Tullgren Funnel test with pictures and additional details.

Standards
Grade 6
Shaping Earth's Surface
2. Topography is reshaped by the weathering of rock and soil and by the transportation
and deposition of sediment.

Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:
e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.

Grade 8
Reactions
5. Chemical reactions are processes in which atoms are rearranged into different combinations of molecules. As a basis for understanding this concept:
e. Students know how to determine whether a solution is acidic, basic, or neutral.

All grades
Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations.

4. Pond Water - Logistics

Time
Creek visit: 5 min introduction 30 min at the creek traveling time to creek and back varies Pond water investigation: 10 min introduction to the proper use and handling of microscopes and slide preparation 30-40 min exploration 10 min wrap up discussion

Grouping
2 students

Materials
Creek visit:

• Small jar or bottle with a sealable lid.
• Optional: 1-2 plankton nets (available for $75 from Science Kit and Boreal Labs OR make your own with panty hose, string, duct tape, a wire coat hanger, and a film canister at The Plankton Net. Plankton nets will greatly increase the number of organisms that you collect although you can simply squeeze the water from water plants, dead leaves, and pond scum into a container.

Pond Water investigation:

For each pair of students:

• 1 eye dropper
• 1 depression glass slide (set of 12 approximately $8 from Science Kit and Boreal Labs or Proaquatica)
• 1 microscope (alternatives to compound microscopes are available on the Sources page)

For whole class to share:

• water sample(s)
• paper towels

Setting
Creek visit: nearby creek, pond, lake, bay or other body of water. Plankton are most commonly observed and collects from water that is fairly still and that has a growth of algae either on the surface or on the rocks and detritus near the bank.

Pond water investigation: classroom

4. Pond Water - Background

Teacher Background
In order to introduce students to the concept of habitats and ecosystems it is often interesting to look at the microhabitats that can be observed only when you look very closely. Plankton which live in ponds, lakes, and other bodies of water form the foundation of the entire aquatic food chain. Students are fascinated by the complexity and diversity of life that can be observed in a single drop of water. If you need to collect plankton yourself, it is best to observe the samples that day or no longer than 1-2 days later. Many plankton are fragile and tend not to survive long outside their natural habitat, particularly at the population density obtained after using a plankton net. However, some plankton can be maintained in the classroom for several days or even weeks under the right conditions - adequate dissolved oxygen and access to a food source. In fact, an interesting extension would be to monitor the types of organisms observed by the class over time as species die out and other increase in numbers.

Student Prerequisites
Experience with microscopes allows students to jump into the classroom portion of the activity more quickly but is not necessary.

4. Pond Water - Getting Ready

Getting Ready Creek visit:

1. Arrange transportation and/or field trip permission slips.
2. Preview the site to ensure a) that there is a large space away from passing cars and other hazards for students to gather and b) that there are pond water organisms near a creek access point.
3. Optional: Get a plankton net or make one.

Pond water investigation:

1. Set up microscopes on student tables.
2. Set out slides, paper towels, eyedroppers, and water samples in an easily accessible central location.
3. Copy or provide copies of identification guides (see Sources page).
4. Optional: make an overhead or create copies of a labeled microscope and rules for microscope handling. (the one I used is downloadable below)

4. Pond Water - Lesson Plan

Lesson Plan
Creek visit:

1. Describe the general plan for the field trip and the goals of the day: 1) to get a sense of the creek environment and 2) to collect a plankton sample to take back to the classroom. You may want to show students where you are going on a map.
2. Set out behavioral guidelines for the trip.
3. Go to the creek.
4. At the creek, tell students that they will be doing a sense of place activity in which they will observe their surroundings using each one of their senses in turn to observe their environment. Each student should find a place to sit at least an arms length from all other students but within ear and eye shot of the teacher.
5. Tell students to close their eyes and quietly take a few long deep breaths and relax a moment. When students stop fidgeting and become still, ask them to notice the smells in the air. How are the smells here different from at school? What can you identify? Think of adjectives to describe the smells.
6. Next stick out your tongue. How does it feel? Are there any tastes in the air? Does it taste cold? Metallic? Sour? Moist? Sweet? Fresh?
7. Next listen to the sounds here. Listen for sounds close by. Listen for sounds far away. What sounds are man-made? What are natural? How are the sounds different from how this place might have sounded a thousand years ago before it was settled by Europeans?
8. Next put your hands on the ground beside you. What do you feel? Are there any objects you can identify without opening your eyes? Pick up some dirt. What is the texture of the dirt? Are all the particles the same size?
9. Finally open your eyes and look at where you are. Look at the living things and the non-living things. Look for natural things and man-made things. Pick one living thing that you think nobody else has notices. Watch it for a while.
10. Allow students time to share their observations with the group. This process of observation helps students connect to their surroundings and notice much more than they would with their eyes open.
11. 5-10 minutes before you need to leave, end the sense of place activity and move to a water access point to collect your water sample.
12. Either squeeze water from the algae, water plants, and dead leaves by the bank into your sample jar OR use your plankton net to collect plankton. To use a plankton net, throw the net as far as possible into the water being sure to hold onto the string. If there is a current, allow the net to drift in the current for a a few minutes. Drag the net back and pour out the contents into your collection jar.
13. Return to the classroom

Pond water investigation:

1. Tell students that they will be looking at the pond water they collected (or that you collected earlier) through microscopes. Their goal is to identify living things and draw pictures of them in their lab notebooks. Define the words organism (Organism - a living thing) and plankton (Plankton - organisms that are found in fresh or salt water and drift with the current, they are usually very small and found near the surface such as algae but may be very large such as jellyfish). Remind them that not all living things move on their own (plants) and to think carefully about their assumptions of what living things are.
2. Give student a brief course or review of proper microscope procedures. Introduce the names of various parts of the microscope.
3. Demonstrate the procedure for making a slide and loading that slide onto the microscopes stage.
4. Divide the students into groups and allow them to get started. Briefly, students will be making drawings of their field of view, identifying the living things in their slide and answering question about them using the student sheet.
5. Allow time for clean up and proper storage of the microscopes and rinsing of the slides.
6. Gather students back to their seats for a discussion of their observations. Some questions to ask include:
   • What kinds of organisms did you observe?
   • Which organisms were most common?
   • How did you determine whether something was living versus non-living?
   • Which organisms were most complex? Which were most simple?
   • How did the organisms move?
   • Could you tell which organisms could make their own food through photosynthesis and which ate other organisms? How?
   • How might the population of organisms that we observed today change over time?
   • What is a habitat? (Habitat - the area where an organism or an ecological community normally lives)
   • What is a microhabitat? (Microhabitat - a very small, specialized habitat such as a drop of water, a fish tank, a pine cone, the area between 2 rocks, etc.)
   • What other microhabitats are there? (a Terraqua column (see Terraqua Column Lesson), the soil critters isolated from a Tullgren funnel (see Soil Analysis lesson).

4. Pond Water - Assessments

Assessment
Research one of the organisms you observed. What does your organism eat? Where is it found? What does it need to survive? Describe its life cycle.

Going Further

1. At the creek, students can write down their observations in a notebook. Encourage them to write down 3 observations for each of their senses.
2. To extend the sense of place activity, students can draw a picture of the creek or write a poem that may be shared with the rest of the class or turned in for homework.
3. Monitor the population of pond water organisms in your water sample over time. Create a class data table with the names and observed numbers of all live species identified on the first day. At regular intervals, repeat the observation and add a new column with new observed population counts. Although this is a very rough measure of the population of organisms over time, certain species will die out over time, an excellent springboard into a discussion of extinction, endangered species, and the causes of population change.

4. Pond Water - Sources and Standards

Sources
This lesson was adapted and inspired by the Pond Water lesson available at Science NetLinks. This site has student worksheets and other excellent resources.
Instructions for building plankton nets can be found at The Plankton Net and Bigelow Laboratory.
The Plankton Net has superb scientific information, photographs, and resources about plankton ecology and marine science in general.
Miscape has a superb cartoon drawing identification key for common pond water organisms as well as information about collecting and maintaining pond water organisms in the classroom.
A superb pond life site can be found at the Sparsholt Schools' Centre. Their "virtual pond dip" is an excellent pond insect identification guide.
The book Pond Life: Revised and Updated (a Golden Guide from St. Martin's Press) by George K Reid is an excellent resource with an identification key for pond life ranging from the microscopic to common birds and mammals.
A great source of information about microscopes and their parts may be found at Microscope.org.
If you do not have compound microscopes (or any microscopes at all) many pond water organisms such as coepepods, ostracods, algae, and insect larvae may be observed with a hand lens. If you have more time or want to integrate an optics project into your pond water investigation, you can build your own microscope out of simple everyday materials. A super microscope plan can be found at the Fun Science Gallery.
Standards
Grade 6
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:
a. Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism
through food webs.
e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.
Grade 7
Cell Biology
1. All living organisms are composed of cells, from just one to many trillions, whose details usually are visible only through a microscope.
All grades
Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
b. Select and use appropriate tools and technology (including calculators, computers, balances, spring scales, microscopes, and binoculars) to perform tests, collect data, and display data.

5. Food Chains - Logistics

Time
45-50 minutes

Grouping
individual

Materials

• 1 copy of organism cards for each student 
• 1 copy of food pyramid overhead for the teacher
• colored pencils
• scissors
• glue sticks
• optional: envelopes

Setting classroom

5. Food Chains - Background

Teacher Background
This activity teaches students 2 things, 1) it reviews the concept of food chains and the major roles of organisms with a food chain and 2) it illustrates the concept of a food pyramid and the transfer of energy from one organism to the next through the food chain. Most students should be familiar with the concept of a food chain and food pyramid from elementary school science, but it is worth at least one class period to thoroughly review these concepts in preparation for more in depth investigations of food webs, ecosystems, and population change.

Food chains are the most simple arrangement of who eats whom assuming that each organism only eats one thing. Of course, in real life this is not the case. Still, it is useful to consider food webs as tangled food chains; therefore, understanding food chains is an essential prerequisite.

The roles that organisms play within a food chain are very well defined. Producers make their own food through photosynthesis. Consumers eat producers or other consumers and may be divided into 4 major categories: herbivores which eat producers, carnivores which eat herbivores or other carnivores, dentritivores (also called decomposers) which recycle the energy from dead organisms to make nutrients available for producers, and omnivores which eat producers and consumers.

Although it is tempting to emphasize that every food chain begins with the sun as the source of energy on which photosynthesis depends, in fact, not all food chains begin with the sun. Organisms near hydrothermal vents at the bottom of the ocean depend on sulfur as the initial energy source. These bacteria use a process called chemosynthesis, taking hydrogen sulfide and oxidizing it, thereby releasing energy. This is typically far more advanced than middle school classrooms although you may wish to allude to the existence of food chains that do not rely on the sun as the initial energy source. For further information, see RESA has a superb website about life at hydrothermal vents.

The concept of a food pyramid adds a level of complexity to the concept of food chains. A producer uses energy from sunlight to grow, reproduce, and survive. Only a small fraction of that energy can be used by a herbivore that eats that producer. Similarly, that herbivore needs to use energy to grow, reproduce, and survive. A carnivore that eats that herbivore does get some energy from that herbivore but only a small percentage. Another way to think of it is to consider how many seeds a plant produces in its lifetime, how many seeds a chicken consumes in its lifetime, and how many chickens a human will consume in its lifetime. Clearly, energy is used and lost at each level of the food chain. Using a food pyramid to illustrate this concept helps students see this visually.

Student Prerequisites
None.

5. Food Chains - Getting Ready

Getting Ready

1. Make copies of organism cards for each student.
2. Make an overhead copy of the food pyramid. If your classroom does not have an overhead projector, you can draw a similar diagram on the board or make a few copies to pass out and for students to share among themselves.
3. Set out colored pencils, scissors, and glue sticks in an easily accessible area.

5. Food Chains - Lesson Plan

Lesson Plan

1. Begin the lesson with the question: “What did you eat for dinner last night?" Break responses down into individual ingredients (separate lasagna into pasta, beef, tomatoes, and cheese) and write them on the board.
2. Once you have a broad sampling, begin categorizing the ingredients into producers, and consumers. Use questions such as:
   • Which of these foods come from plants?
   • Which of these foods don't come from plants? (If mushrooms are on the board, remember that technically mushrooms are fungi not plants!)

   At this point, introduce the idea of producers as plants, or more scientifically, as organisms that make their own food through photosynthesis. Introduce the idea of consumers as animals, or more scientifically, as organisms that eat producers or other consumers.

3. Break down the consumer category further into herbivore, carnivore, omnivore, and dentritivore (or decomposer). Use questions such as:
   • Of the consumers, which are animals that eat plants?
   • Which are animals that eat other animals?
   • Which eat both?
   • Are there any decomposers? (Mushrooms, crab, shrimp, and lobster are likely to be the only decomposers.)

   Introduce the vocabulary words herbivore, carnivore, omnivore, and dentritivore at this point and give the formal definitions.

4. Ask students to describe a food chain. As part of this discussion, try to follow one or more of the foods on the board through the food chain. For example, sun -> corn -> cow -> people. All the food chains we will be dealing with in this class have the sun as the initial energy source although you may want to briefly mention the existence of other food chains that do not depend on the sun (see notes in Teacher Background section).
5. Introduce today's activity. Students should receive a set of organism cards. Their first task is to color code the organisms on their cards by their role in the food chain. Write the color code up on the board: green = producers, yellow = herbivores, red = carnivores, orange = omnivores, blue = dentritivores.
6. When students begin to finish color coding, have students cut out their cards and begin to organize them into food chains. Definitely tell them that there are multiple food chains. If you want, you can tell them how many. When students have identified a complete chain, they can glue it down on a piece of notebook paper.
7. With 10 minutes before the end of class, have students stop and clean up. Any work they have remaining can be assigned as homework. Envelopes can be used to contain any cut out cards that have not been glued down yet. In my classes, about 50% had finished the activity at this point. 50% had to bring home work to finish at home.
8. Once the students have cleaned up and are settled again, put the food pyramid up on the overhead and ask students what they think the picture represents. They should recognize the pictures from their food chain activity. Ask the students why there are more grasses than rabbits and why there are more rabbits than bobcats. Discuss the transfer of energy from one level of the food chain to the next, focusing on how any one organism can't transfer the energy it gets from its food directly to the next organism in the food chain because it needs to use some of that energy itself to grow, reproduce and survive.

5. Food Chains - Assessments

Assessment

1. Complete the food chain activity started in class.
2. Pick an ingredient from your lunch today and construct a food chain. Make sure to start with the sun and include yourself. Identify the role of each organism (producer, herbivore, omnivore, etc.).

Going Further

1. Discuss food chains that do not use the sun as its energy source. NOAA has created a website full of lesson plans for grades 5-12 all about life at hydrothermal vents.
2. Put food chains together into food webs. See Food Web lesson.
3. Look for signs of food chains outdoors. For instance, look for animal scat, insect marks on leaves, and animals foraging. Owl pellet dissections are a fabulous way to bring this back into the classroom. Kidwings provides a great online resource for owl pellet dissections.
4. Bring a rotten log back to the classroom to explore the food chains and mini-ecosystems within. See the Rotten Log Lab Assessment. I used this as an end of the unit assessment tool – which both I and the students enjoyed.

5. Food Chains - Sources and Standards

Sources
The idea for the food chain card game came from Project WILD's book Alaska Ecology available for purchase online for $22. Debbie Breeding's activity Food Chains and Webs provided the information and pictures for the food chain cards. The illustrations on the activity pages are by Paula McKenzie, copied from Mountains to the Sea- A Visitor's Guide to the Santa Monica Mountains and Seashore. Another web resource that provides a similar activity is available from the British Ecological Society. Some of the illustrations on the activity pages are copied from the food chain cards available on their site.

Standards
Grade 6 Ecology (Life Sciences)

5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:

a. Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism through food webs.

b. Students know matter is transferred over time from one organism to others in the food web and between organisms and the physical environment.

c. Students know populations of organisms can be categorized by the functions they serve in an ecosystem.

e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.

6. Food Webs - Logistics

Time
10-20 min introduce activity
45-60 min complete research (some may be assigned for homework)
45-55 min construct food web on classroom floor

Grouping
Individual

Materials
For organism research

• Copies of Field Guide Pages for each student (downloadable below)
• A large assortment of field guides for insects, birds, mammals, fish, amphibians, reptiles, etc.
• Optional: Internet access

For food web activity

• 2-3 balls of yarn
• scissors
• index cards

Setting
Classroom, library or computer lab.

6. Food Webs - Background

Teacher Background

This is a superb activity if you are planning an ecology based field trip or restoration project in an area where local wildlife can be observed. The student research makes students immensely interested and excited about the organisms they might observe in the field. In many ways, this was the highlight of the ecology unit in my students eyes.

The general idea is that students create a field guide to use in the outdoors. Through the process, students gain experience using published field guides, learn about habitats, food webs, and discover threatened/endangered species in their local environment.

I created my list of organisms with a trip to Point Reyes National Seashore in mind. Thus, the creatures represent riparian and coastal California chaparral habitats. If you are planning a trip, the park you plan to visit will usually have a list of wildlife that you can use. I strongly recommend creating your list of organisms to represent local habitats or habitats you plan to visit. If you have too many students for just consumers, consider increasing the number of organisms by including producers as well.

The concluding activity in which a food web is constructed across the classroom floor is fun but often chaotic. I found that 20-30 students can create a complex, representative food web. Therefore it is recommended that you use one class worth of students to assemble a large food web, put away those organisms and start over with the next group of students. Some organisms, such as top carnivores and decomposers are more rare so you can keep those pages available to add to the following class’s food web if you want.

Crowd control in this activity can be quite a challenge if you have an unruly class. In this case, you may want to consider putting the food web together on the board with students still in their seats.

Student Prerequisites
Knowledge of food chains and organisms’ roles within a food chain.
It is helpful if students know what habitats are and how to use a field guide although this can be taught during the lesson.

6. Food Webs - Getting Ready

Getting Ready
For organism research

1. Create a list of organisms for your students to research.
2. If you plan to have students pick an organism out of a hat, create slips of paper for each organism.
3. Collect published field guides for students to use.
4. Make copies of the Field Guide pages for each student.
5. Make 1 copy of a Field Guide page for an overhead. This will be used to give the students an example of what you are looking for. If you want to save some time, this overhead can be created in advance.

For food web activity

1. Clear room of all tables and chairs so that if the students are sitting in a circle around the cleared area at least 10 feet by 10 feet remain.
2. Have yarn and scissors ready to hand out.
3. Create index cards representing the sun, decomposers, and the major producers in the environment. For instance, I created the following cards: sun, decomposers, grasses, seeds, berries, nuts, algae, plankton such as diatoms and copepods, leafy plants. Leave a few blank cards to write on during class as you need them.

6. Food Webs - Lesson Plan

Lesson Plan

For organism research

1. Tell students that they are going to spend the next day(s) researching an organism in preparation for a field trip. Their job is to become the resident expert on their organism and to be able to spot it and identify it when we are in the field. To gather information, they will be using field guides (and the Internet). Tell them how their organisms will be chosen.
2. Show them the overhead of the Field Guide page. Using an organism of your choice, lead them through the field guide page, clarifying any questions and vocabulary words. This is a good opportunity to demonstrate using a published field guide to find information. For example, a "habitat" means the place or environment in which an organism is typically found. The habitat includes where that organism finds food, water, shelter and space. Particularly confusing for some students is concept of diagramming a life cycle. Use your example organism to diagram the life cycle since many students may not have used a life cycle diagram before.
3. Answer any final questions then allow students to pick their organisms and get started. I had my students pick their organism out of a hat and allowed them one extra pick if they did not like their first pick.
4. Circulate among the students as they research their animals, answering questions and helping students who are stuck.

For food web activity:

1. Have students sit in a large circle at the edge of the classroom. Ask for a volunteer to share their animal. Have that student go sit in the middle of the circle. Throughout this whole process, allow each student no more than 1 minute to share since time will run short very quickly otherwise. In the interest of time, I had each student share the animal's food chain, one interesting piece of information from the life cycle, and to describe whether there is anything currently threatening your organism's survival.
2. Ask if anyone has an organism that is part of the same food chain. Encourage that student to share in the middle of the circle. Give the 2 students a ball of yarn and stretch a length of yarn between them.
3. Continue getting students to join the length of yarn until the longest possible food chain is created. Have volunteers help add the sun, a producer, and a decomposer to the food chain using the appropriate index cards. Stretch the line the entire length of the circle and spread the students out evenly along the line.
4. Cut the yarn and set the yarn down on the floor, leaving the student's field guide pages and index cards arrayed along the yarn. The students can rejoin the circle. You should now have a 4-5 organism long food chain that stretches the length of the classroom.
5. Ask if anyone else could have been part of the food chain but was not. Discuss why a food chain is only the simplest representation of who eats who in an ecosystem. Introduce the idea of a food web - tangled food chains that represent the interdependence of organisms in an ecosystem.
6. Begin adding additional organisms to the food web. Give each student an opportunity to share briefly then use yarn to add his or her organism to the food web. Students will discover that some organisms share the same role in the food web, eating the same sources of food and being eaten by the same predators (such as all small mammals: rodents, squirrels, and rabbits). These organisms can all be placed beside one another in the food web and do not need to be connected to other organisms with separate pieces of yarn since they share the same connections as the others next to them.
7. When everyone has shared, ask students to make observations about what they see. Some questions you may want to consider:
   • Why is a food web a better representation of who eats who in an ecosystem than a food chain? Is a food chain useful at all?
   • Where are the producers in the food web? The herbivores? The carnivores? The omnivores? The dentritivores?
   • How many different herbivores are there compared to carnivores?
   • If we had created pages for producers, would you expect there to be more producers or herbivores? Why?
   • How can several organisms share the same food sources and not have 1 organism outcompete the others?
   • Which organisms are endangered/threatened? What does that mean? Why are they endangered?
   • What would happen to the rest of the food web if an organism became extinct? Does it matter if the extinct species is a herbivore or a carnivore? Why?
   • What would happen to the rest of the food web if the habitat was damaged by pollution or construction?
8. Allow some time to gather up the field guide pages, the index cards, and the yarn before the next class enters.

6. Food Webs - Assessments

Assessment

1. Consider the food web you are a part of. Draw as much of that food web as possible.
2. Make a list of 3 ways that food chains are similar to food webs. Make another list of 3 ways that food chains are different from food webs.

Going Further

1. As I mentioned, it is very useful to take the field guide produced by the students on a field trip with you. On that field trip, students can be responsible for tracking the number of different organisms that were observed.
2. Conduct a detailed class investigation of a specific endangered or threatened species and the reasons behind the problem. See the Fighting for Foxes lesson or try the Plight of the Salmon activity available in Monitoring Creek Health.

6. Food Webs - Sources and Standards

Sources
This activity was adapted from Monitoring Creek Health a 6-8th grade curriculum written by the Point Reyes National Seashore Association. Their lesson focued on the insects found in aquatic, creek habitats. I used resources from Point Reyes National Seashore to supplement the list of organisms to research with birds, mammals, reptiles, amphibians, and other species that are commonly encountered in the park. The Point Reyes website has great descriptions of the plant and animal life in the park.

The book Life on the Edge - A guide to California's Endangered Natural Resources by Biosystem Books is a superb resource for identifying and researching endangered and threatened species.

Standards
Grade 6
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and
with the environment. As a basis for understanding this concept:
a. Students know energy entering ecosystems as sunlight is transferred by producers
into chemical energy through photosynthesis and then from organism to organism
through food webs.
b. Students know matter is transferred over time from one organism to others in the
food web and between organisms and the physical environment.
c. Students know populations of organisms can be categorized by the functions they
serve in an ecosystem.
e. Students know the number and types of organisms an ecosystem can support
depends on the resources available and on abiotic factors, such as quantities of
light and water, a range of temperatures, and soil composition.

7. Habitat Survey - Logistics

Time
For habitat survey:
40-50 minutes at the creek
traveling time varies

For setting up the soil analysis tests in the classroom:
10-15 minutes to set up soil separation and Tullgren funnel tests
10 minutes to identify plants and insects

A day later, analyze the results and have a class discussion:
10 minutes to interpret soil separation and Tullgren funnel tests
10 minutes to compare results with another group
20-30 minutes group discussion

Grouping
2-4 students

Materials
For habitat survey, each group of students needs: (I assembled all the materials into several shoebox-sized plastic containers to become our class set of “creek kits”)

• Copy of Habitat Survey handout
• 1 petri dish
• 2-3 strips pH paper
• 10 ml of water (A film canister is a handy, free, container and measuring tool. To be more accurate with your measurements, you can buy plastic, graduated 15 ml test tubes)
• 2-3 white paper towels
• 1 ziplock bag
• 1 extra-large spoon or small hand trowel
• 1 hand lens or magnifying glass
• 4 meter length of string tied into a knot every 1 meter (brightly colored polyester contractor’s string works well)
• 1 roll scotch tape
• optional: bamboo skewers or other sticks/stiff wire to stake out the string

For the habitat survey, the teacher needs:

• first aid kit
• gloves and a plastic bag (for unsavory trash items)
• extra copies of the Habitat Surveyhandout
• field guides of local plants and insects
• optional: water and paper cups

For classroom tests and interpretation each group needs:

• 1 petri dish
• 1 funnel (card stock paper rolled and taped into a funnel shape and cut to 4-6 inches tall may be substituted)
• 1 funnel holder to hold funnels upright above a Petri dish (card stock paper rolled into a tube works well or you can eliminate the Petri dish as well by using a cup that the body of the funnel rests in as long as the bottom tip of the funnel does not touch the bottom of the cup)
• 1 square of cheesecloth
• 1 clear 15 ml tubes with lids, glass or plastic

For classroom tests and interpretation the whole class can share:

• printout of the soil analysis stations directions (see bottom of Soil Analysis lesson summary page)
• 2 tablespoons
• 2 rulers
• 3-4 bare light bulbs hung or mounted approximately 1 foot from the table top (desk lamps work well)
• 1 small jar alum (available at supermarkets for pickling)
• 1 package removable dot labels or rolls of masking tape
• assorted field guides of plants and insects

7. Habitat Survey - Background

Teacher Background
Most of us are familiar with the threats to ecosystems such as rainforests, wetlands, and oceans. Naturally, anything that is a concern on a large scale such as global warming or clear cutting should be studied and researched. However, many organisms do not use an entire ecosystem. Most live in a relatively tiny portion of a larger ecosystem, a microhabitat. In fact many organisms spend their entire lives within a 1 meter square area. It is essential to recognize that organisms do not need an entire ecosystem to be damaged to find that their little microhabitat has been destroyed.

I believe that science skills such as water quality monitoring or soil analysis are of little interest to students unless these skills are applied in the real world to real problems that may not have ready-made solutions. Therefore, after teaching them how to make observations and analyze soil samples in the classroom, I take my students to apply these skills to a real world problem – invasive English ivy that has taken over the bank of a nearby creek. This problem gives students an opportunity to carefully monitor a microhabitat, recognize that ecology happens on a small scale (as well as a larger scale) that an individual person can make a difference on, and create a plan of action to help their microhabitat.

Invasive species are organisms that not only are non-native, but which take over a habitat and out-compete the native organisms. There are many examples of invasive species. Each has a story about where the invasive species came from, how it got to the area, and what adaptations allow this species to out-compete the native species that typically occupy that niche of the food web. English ivy is just one example. It was brought over to America by Europeans who decorated their houses and gardens with this robust, fast-growing vine. In Europe, ivy does not out-compete the plants in the local ecosystems, however, in California, ivy will quickly invade and cover large areas to the exclusion of all other plants.

For middle school students, it is important to draw the distinction between non-native species and invasive species. Not all non-natives are “bad”. One can think of it like diversity in a community of people. Newcomers to a community are welcome and bring new points of view and new ways of doing things. However, if a small group of newcomers start killing off all of the “natives” by crowding them out and taking all the resources then those newcomers are no longer welcome.

This activity plays a role in that the microhabitat survey allows students to observe that there is an extreme difference between those students who have a microhabitat in the ivy covered area and those who have a microhabitat elsewhere along the creek bank. They observe first hand how ivy is invasive and can come to the definition of a native species, non-native species, and invasive species through their own observations. We then decide upon an action plan to restore the ivy area to a more native state and begin our restoration activities. At the end of the year we repeated the microhabitat survey to see how well we did with our goals.

Depending on the message you wish to convey with your own students, the focus of this investigation will vary. I chose to assign half the students sites in the ivy area that we plan to restore and the other half sites in a previously restored area. Other ideas include investigating shaded versus sunny microhabitats, schoolyard versus garden habitats, organic versus fertilized garden habitats, and virtually any other comparison you can imagine.

Student Prerequisites
Soil analysis skills (see Soil Analysis Lesson).
Basic understanding of habitats and ecosystems (see Terraqua Columns, Food Chains, Food Webs, and Ecosystem Organization Lessons).
Ability to use a field guide (see Food Webs Lesson).

7. Habitat Survey - Getting Ready

Getting Ready
For habitat survey:

1. Contact the proper authorities/property owners/neighbors to obtain permission to bring your students to your chosen survey site.
2. Copy Habitat Survey Sheets. Make extra copies of the last 2 pages for the vegetation and insect surveys to bring with you in case students find more examples of plants or insects than their sheet allows them to fill in.
3. Prepare “creek kits” with: petri dish, pH paper, water, paper towels, ziplock bag, spoon or small hand trowel, hand lens or magnifying glass, 4 meter length of string tied into a knot every 1 meter, scotch tape, and stakes.
4. Prepare teacher bag.
5. Arrange transportation to and from the survey site.

For classroom analysis:

1. Set up an example of a Soil separation test and a Tullgren funnel test at each of those stations.
2. Prepare 2 stations around the classroom with the materials needed to conduct that test and a printout of the instructions.

• Soil separation: 15 ml tubes, alum, ruler, labels, 2 different soils labeled in plastic cups, spoons
• Tullgren Funnel: lightbulbs, funnels, cheesecloth squares, funnel holder, petridishes or cups, labels, 2 different soils labeled in plastic cups, spoons

7. Habitat Survey - Lesson Plan

Lesson Plan
For habitat survey:

1. Explain the purpose of today’s investigation to the students before you leave the classroom. If there is a specific question you are investigating, clearly state your question now. The question for my students was “How diverse is the existing ecosystem along the creek bank?” Set out the rules and expectations. You may want to hand out the Habitat Survey Sheets now. I had my students staple each page into their lab notebooks the night before as homework so that each student had a chance to look at the types of data they would be collecting and had a hard surface in which to take notes outdoors.
2. Tell students what teams they will be working with and how to find a survey site (you can assign them there or they may find their own site). Show them how to stake out their survey site with the string and stakes.
3. Depart for the trip.
4. When you arrive, make sure that each team has an appropriate survey site and a creek kit. Make sure that groups are setting up their string and stakes correctly.
5. Allow students to get started immediately collecting the information on their sheets. Circulate among groups to help students who have questions.
6. Teams that finish early can sit quietly with a field guide and try to identify the plants and animals they found.
7. When all groups are finished, return to the classroom.

For setting up soil analysis experiments in the classroom:

1. Tell students to get out their soil samples and Habitat Survey Sheets from their survey site. Tell them that their objective in the next 20-30 minutes isa) to set up a Tullgren funnel with their soil, b) to set up a soil separation test with their soil, and c) to identify the plants and insects at their site using the field guides. Show the students where in the classroom each of these activities can be done. Specify a rotation schedule or divide up the groups to split the work between the team members.
2. Allow students to accomplish each of these tasks, allowing enough time for clean up at each station before rotating to the next area.

For final analysis of results in the classroom:

1. Give students an overview of today’s class and your goals. Remind them of the purpose of this activity and the question you posed at the beginning of this activity. Write this question or your purpose on the board.
2. Allow students 10 minutes to interpret soil separation and Tullgren funnel tests and clean up those stations.
3. When all students are back in their seats, pair each team of students up with another team and ask them to compare their results. Tell them that they will report back to the whole class about a) similarities between their survey sites, b) differences between their survey sites, and c) anything that surprised them during this investigation. On the board, below where you wrote down the question or purpose, create a table with the following columns: Similarities, Differences, Surprises. Give the students 10 minutes to discuss their results with another team.
4. Allow each pair of teams to share their findings with the class. Write up their discoveries on the board.
5. Once all pairs of teams have shared, begin a class discussion. Some discussion questions you may want to consider include:

• What similarities did groups find? Why might those similarities exist?
• What differences did groups find? Why might those differences exist?
• Why did you find certain things surprising? What did you expect at the beginning?
• These small habitats are considered microhabitats. What factors in the environment might create microhabitats? (examples include a road or path that divides one area from another, areas of shade or sunlight, proximity to a water source, etc.)
• What creatures might live their whole life in only one microhabitat? What creatures wander from one microhabitat to another?
• Were we able to answer the question with the data we collected?
• Are there additional observations we could have or should have made to better answer the question?
• Is the area we studied a healthy habitat? Why or why not?
• Is the area we studied a sustainable habitat? Why or why not?
• What could or should be done to improve this area? Could we as a class do anything to improve it?

7. Habitat Survey - Assessments

Assessment

1. Ask one or more of the discussion questions as a homework/assessment question. In particular, the question “Is the area we studied a healthy habitat? Why or why not?” and “What could or should be done to improve this area?” are excellent questions for students to think more deeply about.

Going Further

1. Conduct a restoration project at the survey site! Turn the student’s good ideas into an action plan to improve the habitat.
2. Have students research and design a balanced, diverse and sustainable ecosystem for the are they studied. See Ecosystem Plan Project for concrete ideas of how to structure this research project.

7. Habitat Survey - Sources and Standards

Sources
The idea for this activity came from several other lesson plans designed for transect survey sites. I was inspired by the following lessons:
“On-Site Lesson Plan” in Monitoring Creek Health
“Activity 7: Microhabitats” in the book Environmental Science Activities Kit : Ready-To-Use Lessons, Labs, and Worksheets for Grades 7-12 by Michael Roa
“Weeding Out – River Plant Survey”, “A Matter of Trash – Pollution Survey” and “Macroinvertebrate Investigation” from Friends of the LA River’s science curriculum

See the Soil Analysis Lesson for source information about the soil analysis tests.

You can obtain 15 ml graduated test tubes from BD sciences.

Standards
Grade 6
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:
a. Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism through food webs.
b. Students know matter is transferred over time from one organism to others in the food web and between organisms and the physical environment.
c. Students know populations of organisms can be categorized by the functions they serve in an ecosystem.
e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of
light and water, a range of temperatures, and soil composition.

Grade 8
Reactions
5. Chemical reactions are processes in which atoms are rearranged into different combinations of molecules. As a basis for understanding this concept:
e. Students know how to determine whether a solution is acidic, basic, or neutral.

All grades
Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform
investigations.

8. Ecosystem Organization - Logistics

Time
45-55 minutes

Grouping
Individual

Materials

1. Copies of blank Ecosystem Organization Pyramid
2. Overhead copy of the Ecosystem Organization Teacher Pyramid
3. Colored pencils
4. Optional: photographs or posters of various biomes (I recommend cutting out magazine photos from National Geographic or Smithsonian Magazines or getting old landscape photography calendars when they go on sale in March or April.)

Setting
Classroom

8. Ecosystem Organization - Background

Teacher Background
In order to study ecology, scientists need to see how organisms are related to one another and also to the environment in which they live. To do this, it is useful to think about a hierarchy of ecosystem organization ranging from the individual organism to the biosphere.

To begin with, consider a single organism, the individual. An “organism” is any living thing, whether it is a human being, a germ, a rose bush, or a panda bear.

A group of organisms of the same kind is a population. A “population” can be defined as a group of interbreeding organisms living in the same area. You might imagine a human population such as the population of the city in which you live or the population of a certain country. The humans within that population live in the same area and can interbreed and have babies. Similarly, a population of dandelions might all live in the same field and share pollen or a population of dolphins might all live in the same body of water and have babies.

A community is the next largest level of organization. A “community” includes all the organisms, sometimes hundreds of different types, in a given area. Several different populations are usually found in a community. The populations within a community are interdependent because of the food webs that bind them together. Communities can vary greatly in size. For instance, you could consider the community within a certain forest or you could think about a community in a garden. In MyScienceBox, students study microhabitats and look at a community within a single square meter. Communities can be even smaller such as the community that lives on and inside a single human being. On our skin are various molds, yeasts, and bacteria. In our hair we may have lice. In our intestines are E. coli and other bacteria. Many microscopic critters live in our mouth. Thus, there is a community of organisms living in and on your body!

Until now, we have only considered the living things in an area. The next level of the organization, an ecosystem, begins to include the nonliving parts as well. An “ecosystem” includes all organisms in a defined area and their nonliving environment. When you study an ecosystem, you look at how the nonliving and living parts affect one other. When you study a community, you only look at how the living things affect each other. Like a community, an ecosystem can be large or small. The Earth is the largest of all ecosystems which is called the “biosphere”.

The Earth ecosystem can be divided into several major biomes. A “biome” is one of several major types of ecosystems found on the planet. Each biome is characterized by a particular type of vegetation. Biomes generally encompass large geographical areas and are not sharply delineated (one will blend into another). You probably are already familiar with the major biomes already: desert, rainforest, grassland, tundra, coniferous forest, deciduous forest, and mountain. Some include the ocean as a non-terrestrial biome. One important point is that even though a biome like a rainforest will be similar anywhere in the world – all will have large trees, vines, many bird and animal species, etc. – the exact type of species of tree and the exact type of vine will vary from rainforest to rainforest. Thus in one kind of biome, different organisms will occupy the same niche. These organisms tend to be similar in form but often come from very different evolutionary backgrounds (for instance, consider the numbat, an Australian marsupial anteater, and other mammalian anteaters around the world including the giant anteater and the armadillo).

Student Prerequisites
Some understanding of food webs is useful but not required.

8. Ecosystem Organization - Getting Ready

Getting Ready

1. Make copies of the Ecosystem Organization Pyramid
2. Set out colored pencils
3. Collect and display photographs or posters of various biomes

8. Ecosystem Organization - Lesson Plan

Lesson Plan

1. I began this lesson with a visualization exercise. When all students are seated, instruct them to close their eyes and imagine an animal, anything they want as long as it lives in the wild (not a dog, cat, horse or other domesticated animal) and they know something about it.
2. First have them think about their animal alone as an individual. What does it look like? How does it move?
3. Then imagine this animal interacting with others of its kind. Does your animal live alone or in a group? How does it take care of its young? How does it interact with other adults of its species?
4. Next think of other types of living things your animal might interact with. What does it eat? What eats it? Does it depend on grasses or trees for shelter or making a nest? Does it compete with other types of animals for food?
5. Next think of the non-living things that your animal interacts with. Where does it live? Where does it find water? What type of soil does it live on? What is the weather like where it lives?
6. Finally, think about your organism in relationship to the whole planet Earth. Imagine a picture of the Earth from space. Where on the planet does your animal live? How does its life affect the lives around it? Hoe does its life affect you?
7. Have the students open their eyes. Tell them that in their imaginations they zoomed out from one individual organism to the whole planet. Ecologists who study organisms and their environment think about organisms and their environment at different levels of “zoom”. Some study at small groups of the same kind of animal – like Jane Goodall who studies chimpanzees in Africa. Some study a whole type of ecosystem, like rainforests or deserts and all the creatures that live within it. Some study the whole planet. Today we will be thinking of the words ecologists use to describe the various levels of “zoom” and will be drawing a picture to illustrate these different levels.
8. Give students the blank student copies of the Ecosystem Organization Pyramid while you put the Teacher version on the overhead. (If you are short on time, you can give students the Teacher version directly and not have them copy the words and definitions.) Discuss each of the words that defines each level of the organization and have students copy the words and definitions onto their copy. Allow lots of time for questions, showing pictures of biomes, and discussion of the different levels. In particular, pay attention to the fact that the top 3 levels only include living things while the bottom 3 levels include the nonliving environment as well.
9. Tell students that they should now fill in the center of their pyramid with drawings of their animal within each level. For example, the top should be a picture of their animal by itself as an individual. The next teir should show their animal with others of its species. And so on. If you choose, it is helpful for students to use the right side of the pyramid for a short caption explaining their picture. For example, the second teir might say, “Kody the Koala and the koala bear family and friends that live in his forest.”
10. Students who take longer to finish the drawings can take them home to finish as homework.

8. Ecosystem Organization - Assessments

Assessment
Use a quick quiz the following day to test vocabulary retention. For example:

Match the example to the correct word. Write the letter of the correct word in the blank beside the example.

a) ecosystem
b) community
c) biome
d) individual
e) population
f) biosphere 

____    Rosie the rattlesnake                   
____    rattlesnakes, mice, small birds, crickets, grass, hawks, cacti, and tumbleweed               
____    the entire planet Earth                   
____    the community, the water, the air, the rocks, the soil, and the mountains
____    a desert
____    all the rattlesnakes in the area

Going Further

1. Return to the Field Guide produced from the Food Web activity to discuss and further investigate the community, ecosystem and biome represented by the organisms in the field guide.
2. Research the Biosphere 2 project in which 5 biomes are replicated in an airtight facility in Arizona. Why was this center built? What scientific questions can be discovered? How is Biosphere 2 similar to Biosphere 1 (the real planet Earth)? How is it different?

8. Ecosystem Organization - Sources and Standards

Sources
For more information about biomes around the world, see the Blue Planet Website

For more information about Biosphere 2, see the official website of Biospheres 2 or this Biosphere site that contains additional information about the research and history of the project.

Standards
Grade 6
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:
c. Students know populations of organisms can be categorized by the functions they serve in an ecosystem.
d. Students know different kinds of organisms may play similar ecological roles in similar biomes.
e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.

9. Hare and Lynx - Logistics

Time
45-55 minutes

Grouping
Individual

Materials

1. Copy of the Hare Lynx Questions and blank Hare Lynx Graph for each student. This handout is designed so that you can give students just the data and blank graph and discuss the interpretation as a whole class OR you can give students a handout with questions that will lead them towards one of several theories.
2. Overhead copy of the blank Hare Lynx Graph to chart along with the students OR overhead copy of the completed Hare Lynx Graph.
3. Field guides or other pictures and background information about snowshoe hares and the Canada lynx

Setting
classroom

9. Hare and Lynx - Background

Teacher Background
After learning about habitats, food webs and food chains, students can begin to discover the relationships between organisms and between organisms and their environment. A key to many of these studies to the investigation of how populations change over time.

Populations are always changing. Sometimes changes are the result of humans interfering with food webs or habitats. But even when humans do not interfere, populations will still naturally shift up and down or fluctuate. As an example, we will look closely at the relationship between the Canada lynx and its primary prey, the snowshoe hare – an example touted in nearly every ecology textbook and population biology course.

The snowshoe hare is a common species of rabbit found in North America, its range extending throughout Canada, Alaska, and into the northern United States. One distinctive quality is its 2 different coloration patterns – brown in the summer, and white in the winter to better camouflage with the snow. Its diet consists of grasses, berries, twigs, bark and leaves.

The Canada lynx is a wild cat that resembles a large house cat with a short tail and prominent tufts on its ears. It is very secretive and even experienced hunters rarely see one in the wild. Its range overlaps with the snowshoe hare, on which it almost exclusively preys upon.  

For over 300 years, the Hudson Bay Company has been involved in the fur trade in Canada. Detailed company records list the number of snowshoe hare pelts and the number of lynx pelts collected by hunters and trappers every year since the late 1700’s. The data shows a 200 year history of cyclical population booms and busts in the snowshoe hare population and a slightly delayed population boom and bust in the lynx population. Native Americans observed this cycle long before Europeans began trapping the hares and lynx for their pelts. Yet there are many competing theories to explain why the populations cycle in so dramatic a fashion. These theories include:

During peak years, the hares devour all the available vegetation and quite literally breed like rabbits until the environment can no longer support their blossoming population. As the hares become weakened by starvation, the lynx are better able to find and kill them, adding to their decline. The population does not reestablish itself immediately because it takes time for the vegetation to grow back.

Another theory is that the lynx population determines the hare population. As the number of hares increases, so does the numbers of lynx that survive to eat them. Soon, there are too many lynx for the number of hares and the lynx eat away their favorite food until they too suffer a population decline until the hare population can start growing again.

Lastly, there is evidence that at the peak population levels, the hares become so stressed by the increasing numbers of predators that they no longer reproduce at the same rate. Their population falls both as a result of the lowered reproductive success and the sheer number of lynx that are out to eat them.

Although the subtleties of these theories may be too complex for the typical middle schooler, their understanding of food webs and intuitive understanding of predator-prey relationships will likely enable them to piece together the general picture well enough for it to make sense.

Student Prerequisites
A clear understanding of food webs (see the Food Web activity).

An intuitive understanding of predator-prey relationships.

Experience with graphing data on an x-y coordinate system. This is essential! For students only recently introduced to graphing, consider giving students the completed graph and carefully walk them through its interpretation.

9. Hare and Lynx - Getting Ready

Getting Ready

1. Make copies of the handouts for the students (either copy the entire handout if using the questions or just the first page and the graph page if the interpretation of the data will be done as a whole class discussion).
2. Make overhead for the teacher.
3. Collect background information about the snowshoe hare and Canada lynx from field guides or other information (see Sources).

9. Hare and Lynx - Lesson Plan

Lesson Plan

1. Introduce today’s activity to the students. Remind them of the definition of a population and discuss how we will be looking at how populations change over time.
2. Introduce the snowshoe hare and the Canada lynx to the students. Show them pictures. Discuss their appearance, life cycle, range, habitat and diet.
3. Give students the handout and read the first paragraphs together. Graph the data, either together as a class using the teacher overhead, or individually.
4. Ask the students to describe some of the patterns in the graphs.
5. Begin a discussion with the students about why they think these patterns exist. Allow the discussion to be open ended so long as their explanations make logical sense. The purpose of the discussion is not to decide on the true reason that the cycle exists but to encourage students to come up with a logical theory based on the evidence and what they know about ecology. Some examples of questions you may wish to ask include:

   • Notice how the hare population begins to increase over time until it reaches a peak. Why do you think that the numbers of hares are increasing at this time?
   • Notice how the hare population begins to decrease after the peak. Why do you think that the numbers of hares is decreasing at this time?
   • In general, are there more lynx or more hares? Why?
   • Do the peaks in the lynx graph line up exactly with the peaks in the hares graph?
   • When the hare population increases, what happens to the lynx population? Why?
   • Look at the lynx population in 1903 and 1904. Think about what is happening to the hares at this time. Is the presence of more lynx helping the hares or hurting them? Why?
   • Look at the lynx population in 1904 to 1906. Why is the lynx population declining?
   • Do you think that this pattern is still happening today?

6. Help students summarize their theory by adding arrows and labels to the graph to explain what is happening according to the theory at different times.
7. Once the students have created a logical theory, you may want to consider asking them to think of experiments that could test their theory. For example, if they believe the hares are overeating the available vegetation, then a good experiment might be to monitor the population of the hares’ favorite foods over a number of years.

9. Hare and Lynx - Assessments

Assessment

1. Have students summarize the theory they came up with in their own words.
2. Provide another example of population change data and have students, individually or in groups, graph the information, interpret the data, and create a theory. For example, see the Coho Salmon Graphing worksheet (downloadable below).

Going Further

1. The JASON project, provides a year long, interdisciplinary curriculum linked to real world scientific expeditions. They created a superb series of lessons about the Channel Islands in California called “From Shore to Sea”. Story 4 of the curriculum deals with kelp forest monitoring and has students graph information about the population density of sea urchins and of kelp plants. They discover a relationship between kelp and sea urchins as well as El Nino events.
2. The Project WILD K-12 Curriculum and Activity Guide has several great population change activities. My favorites are the “How many bears can live in this forest?” and the “Oh deer!” activities. Both are outdoor games that illustrate the idea of population change, limiting factors, carrying capacity and can be used to graph population changes over time.
3. A similar game was developed to look at wolf populations by a group of teachers through the Columbia Education Center's Summer Workshop.
4. The United Nations recently developed a set of 8 Millenium Goals that were set by UN leaders to combat extreme poverty. Much of this debate centers on the growing human population of the planet and the simultaneously diminishing environmental resources. A great layperson’s discussion of the debate can be found in a recent edition of Scientific American, September 2005. Global population data can be found at the Global Population Database. The Population Resource Bureau has a list of lesson plans for teachers related to global population statistics.
5. Although written for grades 9-12, this lesson plan by the Sierra Club on California’s sequoia forests gets into really interesting issues of population control and forest management.

9. Hare and Lynx - Sources and Standards

Sources
Of the many websites that explore the relationship between the hare and the lynx, by far the most dynamic and engaging is CBC Television’s production of Walking with Ghosts. The Overview section has detailed information about the hare, lynx, population cycles and even about predator biologists. Unfortunately, I was never able to figure out how to order a copy of the program. Please add a comment if you are able to get a copy!

Other resources about the hare-lynx population cycle include:

• An article from the National Wildlife Association discussing the effect of global warming on the hare and lynx.
• Information from at Hinterland’s Who’s Who website about the hare and lynx.
• A scientific review article (Krebs, C. J., R. Boonstra, S. Boutin and A. R. E. Sinclair. 2001. What drives the 10-year cycle of snowshoe hares? BioScience 51:25-35), available below as a pdf document.

Standards
Grade 6
Ecology (Life Sciences)
Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:
Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism through food webs.
Students know matter is transferred over time from one organism to others in the food web and between organisms and the physical environment.
e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.

10. Gone Fishin' - Logistics

Time
45-55 minutes

Grouping
Teams of 4 students

Materials

1. Copy of Tragedy of the Commons handout for each student.
2. 1 carton goldfish crackers
3. 1 bag M&Ms (if sweets are not allowed, any small food item will work, grapes, raisins, cheerios, almonds, etc.)
4. 1 bag peanut M&Ms
5. 1 jar salted peanuts
6. 1 roll masking tape or scotch tape per group of 4 students
7. 1 paper plate per group of 4 students
8. 1 napkin or paper towel per student
9. 2 drinking straws per student
10. Optional: 4 plastic spoons for transferring fish from the teacher’s stocks to the student oceans

Setting
Classroom

10. Gone Fishin' - Background

Teacher Background
The tragedy of the commons was initially proposed as a hypothetical model to illustrate a much larger societal problem. In colonial times, there was often a common pasture (the commons) where all citizens of the town could take their livestock for grazing. Each individual farmer and his animals is motivated to use this pasture land to get the maximum benefit possible. However, as more animals use the resource, the pasture gets trampled and overgrazed until there is no grass left for anyone. Thus, if each farmer is motivated simply to maximize personal benefit, thus using the pasture as much as possible, the resource is soon no good to anyone.

Similarly, the ocean’s supply of fish is a common resource that is rapidly being depleted. The basic issue is that since 1950, the fishing industry has quadrupled its catch. According to the United Nations, 15 out of the 17 world fisheries are overfished or depleted. 90% of the large fish species in the oceans have been fished out in the last 50 years. In short, fish are being taken from the oceans faster than they can reproduce and grow. Many fisheries have already collapsed, sending hundreds of fishermen and women out of work. Without clear international controls and regulation, soon there will be no more fish in the seas. Many articles have been published in recent years describing the problem. For example, see the Economist, May 2005, Science Magazine, December 2003, and the San Francisco Chronicle, October 2004.

This activity is a way to help students recognize the problem by catching candy, peanut and cracker fish from paper plate oceans. Students will spend 4 years fishing in their oceans. Each “year” the students have 30 seconds to fish for as many fish as they can catch using straws and masking tape as their poles and hooks. Each fish has a different monetary value and each student much catch a minimum dollar amount of fish in order to stay in business the following year. Then the remaining fish in the ocean have a chance to reproduce. There must be at least 2 fish of that species to reproduce. In addition, the fish in their oceans have a food web and must have their food source still available in order to survive.

At the end of the game, some oceans will likely have overfished their fishery until there are no fish left. Others will have developed a strategy in order to maintain a sustainable fishing industry. The discussion at the end will look at the problem of overfishing and solutions that lead towards sustainable resource management. The stage is then set for solid discussions of resource management strategies for other shared environmental resources.

Student Prerequisites
Students need a solid understanding of food webs (see Food Webs activity) and experience with monitoring population changes over time through tables and graphs (See Hare and Lynx Population Change activity).

10. Gone Fishin' - Getting Ready

Getting Ready

1. Copy student handouts
2. Collect materials for the activity and set them out for easy access. In particular, you may want to make a tray for the teacher with the 4 different “fish” in separate bowls that can be easily carried around the classroom.

10. Gone Fishin' - Lesson Plan

Lesson Plan

1. Begin class with a discussion of fishing. What kinds of fish do you eat? What do you know about where fish come from and how they are caught? Who has ever gone fishing before?
2. Introduce today’s activity. Students will become fishermen and women for the day. These are the criteria/rules for the game:

   • 4 fisherpersons will be fishing in each ocean (a paper plate). You cannot touch, tip or move the ocean!
   • Each fisherperson will be given 2 fishing poles (straws) and a net (a short length of tape) to fish with. There should be NO fishing with hands! Each fisherperson will also get a boat (a napkin) onto which any fish that are caught should be placed. Fish that fall out of the boat onto the table do not count!
   • You will be fishing in your ocean for 4 years. Each year you will have 30 seconds to bring in your catch.  
   • There are 4 different kinds of fish in the ocean. Each is worth a certain amount of money on the market. Goldfish are worth $3, Peanut Fish are worth $5, M&M Fish are worth $5, and Peanut M&M Fish are worth $10.
   • You must earn at least $5 of income each year to stay in business. However, you should try to earn as much money as possible.
   • At the end of each year, the fish have a chance to reproduce. For every 2 fish of that species, they will make 2 baby fish. Fish mate in pairs. Single fish don’t reproduce.
   • The fish exist in a food web and need to have food in order to survive. Goldfish eat seaweed of which there is always a lot in the ocean. Peanut Fish and M&M Fish eat Goldfish; there must be at least 1 Goldfish in the ocean for these fish to survive. Peanut M&M Fish eats both Peanut Fish and M&M fish; there must be at least 1 Peanut Fish and 1 M&M fish in the ocean for these fish to survive.

3. Pass out the data tables and handout. Have one person from each group collect a plate, 8 straws, 4 napkins and a roll of tape for the members of their group. Students may use the straws and tape to create any fishing device they want. The key is to get fish out of the ocean and safely onto their boat.
4. Meanwhile, the teacher should go to each ocean and start off each ocean with: 4 peanut M&Ms, 4 peanuts, 4 M&Ms and 4 goldfish. If students discuss strategy at this time, let them. But have them do it spontaneously rather than instructing them to discuss strategy with their group.
5. When all oceans are stocked and groups are ready, the teacher should say “GO” and give students 30 seconds to fish. When the teachers says “STOP” all fishing poles must be put down.
6. Students should fill in their data tables with the number of each species of fish that remains in the ocean, the number and value of their catch, and the income earned by each fisherperson in their group. Once their tables are filled out, they can eat their catch!
7. As they fill in the tables, go around and adjust the number of fish in each ocean for the next round. Remember, there must be a food source and 2 fish of that species for them to reproduce and survive.
8. Repeat steps 5-7 three more times until there have been 4 years of fishing.
9. You may want to have students work on the worksheet questions at this time. The first 3 questions are good places to have students think about their own ocean before comparing the results between groups. You can also save the worksheet for homework or for after a group discussion.
10. Have each group report to the class the final number of fish remaining in their oceans after year 4. Some oceans may be completely empty of fish. Others may have figured out a way to fish sustainably so that there are many more fish than when they started. Discuss the various strategies the different groups used (or didn’t use) to manage their oceans.
11. Introduce the concepts of overfishing, environmental collapse, the tragedy of the commons, sustainability, and resource management as they become relevant to the discussion.
12. Discuss other common resources that suffer from a tragedy of the commons and think about strategies that we can use to manage those resources responsibly.

10. Gone Fishin' - Assessments

Assessment

1. The Gone Fishin’s Questions can be used as a written assessment of what the students took away from this assignment.
2. Have students read an article that discusses the problems facing the oceans’ fisheries (see Teacher Background for some examples) and write about the issue from the point of view of one of the many stakeholders (the fishermen and women, politicians, seafood restaurant owners, park rangers, etc.).
3. Have students bring to class some real numbers and data about the state of fisheries in the world today. The National Oceanic and Atmospheric Association has a great educators resource for researching information about fisheries as well as suggestions for other activities to try. The Monterey Bay Aquarium also has many resources related to the conservation of ocean resources. In particular, students would benefit from learning about sustainable fishing practices and how to make responsible choices when buying seafood. The Seafood Watch portion of the Monterey Bay Aquarium Website has excellent information for helping students make educated choices.

Going Further

1. There is an excellent video called “Empty Oceans Empty Nets” produced by PBS that discusses the fisheries problem.
2. One direction to take this is into the realm of game theory, the economists’ and mathematician’s attempt to model human (and even animal) behavior through simplified scenarios. One of the most famous game theory scenarios is the prisoners’ dilemma in which 2 conspirators are arrested and placed into separate holding cells to be questioned. If both stay silent, then they both get light sentences. If both provide evidence against the other, then both get harsh sentences. If one stays silent and one provides evidence against the other, then the tattle-tale goes free while the betrayed gets a harsh sentence. This scenario alone has been observed to have many biological applications. For resources related to game theory, see the Game Theory Website.
3. Finally, there are many other commons problems that students can research as a class or independently. These include logging, poaching, hunting, air quality, water quality, pollution, population growth, e-mail spamming, traffic congestion, and more.

10. Gone Fishin' - Sources and Standards

Sources
The idea for this lesson came from Jen McGonigle, a science teacher from Haddonfield, New Jersey, who shared this activity during the Exploratorium’s Summer Teacher Institute.

Wikipedia has a wonderful summary of the tragedy of the commons. It includes an excellent review of Hardin’s original essay on the topic, historical background about where the concept of the commons originated, and many examples of modern commons problems: littering, air quality, water quality, population growth, logging, etc.

Standards
Grade 6
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:
a. Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism through food webs.
b. Students know matter is transferred over time from one organism to others in the food web and between organisms and the physical environment.
e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.

Grade 6
Resources
6. Sources of energy and materials differ in amounts, distribution, usefulness, and the time required for their formation. As a basis for understanding this concept:
b. Students know different natural energy and material resources, including air, soil, rocks, minerals, petroleum, fresh water, wildlife, and forests, and know how to classify them as renewable or nonrenewable.

All Grades
Investigation and Experimentation
7. c. Construct appropriate graphs from data and develop qualitative statements about the relationships between variables.

Fighting for Foxes - Logistics

Time
30-45 minutes

Grouping
Individual

Materials
Copy of the Fighting for Foxes article (downloadable from the summary page or from Smithsonian Magazine).
Copy of the Reading Questions .
Field guide with information about golden eagles.
Field guide with information about Channel island foxes.

Setting
classroom

Fighting for Foxes - Background

Teacher Background

The causes and complexity of protecting endangered species is a hot topic in the media and environmental policy. For students to become educated consumers of scientific information in the media, it is essential that they gain exposure to these issues and discover that saving an endangered species is never as simple as it seems. The Channel Island fox is a fascinating example because its story involves several other charismatic species, the bald eagle, the golden eagle, and feral pigs. I encourage you to seek out other articles describing the plight of endangered species in your local area. If you find any good ones, add your comments below to let other teachers have access to your resources.

Student Prerequisites

Students should have been exposed to the following concepts: food webs, habitats, and endangered species.

Fighting for Foxes - Getting Ready

Getting Ready

1. Make copies of the Fighting for Foxes article.
2. Make copies of the Reading Questions.
3. Write the following instructions on the board: “As you read, underline any information that seems important to create a. a food chain for the bald eagle b. a food web for the golden eagle”

Fighting for Foxes - Lesson Plan

Lesson Plan

1. Tell students that they are going to read an article about channel island foxes from the a recent issue of Smithsonian magazine then answer some reading questions. Draw notice to the instructions on the board.
2. Go around the room having one student read aloud for a paragraph or a few sentences. You may want to point out information relevant to creating the food chain and food web when it appears so students are reminded to unerline those sections.
3. Stop after the description of the bald eagles and DDT contamination. Have students read the first question on their questions sheet and give them a few minutes to create a food chain for the bald eagle. Encourage them to work together if they need help. You may want to discuss some of the food chains that students created and write an example up on the board.
4. When everyone has had an opportunity to write down something, continue reading as a group. Stop after the description of the golden eagle diet. Have students read the second question on the reading questions page.
5. Ask students if there is enough information about golden eagles to create a food web? What other information is needed? Ask for volunteers to use the field guides to find out more information about golden eagles and Channel Island foxes. Write the information on the board.
6. When students have gathered enough information, give students 10-15 minutes to create a food web for the golden eagle. If they are having trouble, tell them to start with the “channel island fox” in the middle of their page. Write the names of what the fox eats above it and write the names of what eats the fox below it. Draw arrows to represent relationships.
7. Before reading any more, have students read question 3 and answer it based on their food webs.
8. Finish reading the article together. Give students 10-15 minutes to answer the remaining questions or assign those questions for homework.

Fighting for Foxes - Assessments

Going Further

1. Research another endangered species. Create a food web for your species. Describe the circumstances that led to your organism’s decline and the steps that are being taken to allow the population to recover. If you don’t want students to research their own species, consider using other articles from magazines or books. The book Life on the Edge – A guide to California’s Endangered Natural Resources by Biosystem Books is a superb resource for identifying and researching endangered and threatened species.
2. Create an action project to educate other students, parents and/or the community about an endangered species in your area. Consider creating newsletters, creating a web page, or making a presentation to younger grades.

Fighting for Foxes - Sources and Standards

Sources

The original Fighting for Foxes article from Smithsonian Magazine is available free online. Several additional articles about the foxes and other endangered species in California are available through Smithsonian as well.

Standards

Grade 6

Ecology (Life Sciences)

5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:

a. Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism through food webs.

b. Students know matter is transferred over time from one organism to others in the food web and between organisms and the physical environment.

e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.

Point Reyes - Planning Guide

Bear Valley Visitor Center ranger program
This program gave students the opportunity to use their water quality monitoring skills in a real world situation. This program comes with a superb hands-on curriculum for use in the classroom before and after the program. Students create a map, measure the temperature, measure pH, measure dissolved oxygen, measure the channel width and depth, measure the velocity of the water, and survey the insects present in the creek. They briefly discuss their results as a group with the ranger but the bulk of the discussion happens when the data is brought home to the classroom. The Post-Visit Activities included in the curriculum are both excellent and essential to bring closure to the experience. The creek monitoring experience provides a springboard with which to plan a water and soil monitoring program at a local creek near the school.

You must make reservations in advance to participate in the park's ranger led programs. In addition to Monitoring Creek Health, there are a number of other ranger led programs focusing on different aspects of geology, ecology and natural history. Reservation forms can be found on the Point Reyes website. Reservations must be in writing and are accepted on a first come first served basis. Call 415-464-5139 for available dates and more information.

Camping at Olema Ranch Campground
Olema Ranch Campground is a privately owned campground located half a mile from the Park. Several large group sites are available. Tent sites start at $25 per site. Each site accommodates up to 6 people and 2 cars. The facilities have showers, fire pits, picnic tables, and a general store. They also have games you can borrow such as horseshoes, croquet, shuffleboard and others. For more information, call (415) 663-8001 or e-mail the campgrounds at [email protected]

Kayaking with Blue Waters Kayaking
Our school has gone kayaking with Blue Waters Kayaks for many years - always with the greatest success. The program I can heartily recommend is the 6 hour paddle out of Inverness. Students learn the basics of handling a kayak then slowly make their way 1.5 miles along the bay to a lovely beach. There, students have lunch and explore the estuary and its wildlife before returning. While I personally have only been on the 6 hour kayaking programs with my students, Blue Waters can also arrange kayak camping trips along Tomales Bay. The prices for groups varies so contact Blue Waters directly for rates and information 415-669-2600.

Ecosystem Plan - Logistics

Time
3-4 hours

Grouping
Groups of 2-3 students    

Materials

1. Field guides
2. Lists of local native plants and animals. For the lists I used for my students who were restoring a creek-side area in California, see the Sources area for several great resources.
3. Copy of the Ecosystem Plan Assignment Sheet for each group or for each student
4. One piece of posterboard or flip chart paper for each group
5. 20 index cards for each group
6. Construction paper
7. Markers
8. Glue sticks
9. Scissors

Setting
classroom

Ecosystem Plan - Background

Teacher Background
In this activity, students will put together all they know about food webs, habitats, ecosystems, and the interactions between organisms and their environment to try to design a diverse, balanced, and sustainable ecosystem. One of the most important things for students to recognize from this activity is the idea that an ecosystem works together as a unified whole rather than as individual plants and animals living independently in an environment. The plants depend on the available growing conditions of the topography, soil quality, water availability, temperature and sunlight. In turn, the animals depend on the availability of plants for food and shelter. And the whole ecosystem depends on us to set it up in a balanced way so that it can sustain itself in the long run.

Another key lesson is that of biodiversity contributing to greater ecosystem health and sustainability. In general, the more diverse an ecological community, the more likely it is to flourish in the long run. If multiple organisms fill each niche, then when trouble hits one organism, the role can still be filled by another. An interesting analogy can be made to diversity in human communities. You may want to consider opening the discussion of biodiversity with the question, “Why do we as teachers try to encourage diversity in the classroom? Why does diversity help make better communities?”  Allow this to lead you into the idea of why biodiversity might lead to more sustainable ecosystems.

Finally, it is essential that you and the students have a very clear picture of the area that you will be designing the ecosystem for. The environmental conditions such as the landscape, sunlight, water, rainfall, soil quality, and general size of the space will greatly affect the types of plants and animals that can survive in that place. In addition, if the area is used or accessed by humans, that will greatly affect the types of plants and animals that can survive. Every plant and animal the students choose must be able to live in these conditions. Therefore, the more intimate the students’ knowledge of the environmental conditions, the easier it will be for them to keep those conditions in mind when choosing their species.

Student Prerequisites
A solid foundation in food webs, what ecosystems are, resource management, native vs. non-native species, and experience observing environmental conditions such as soil quality and water availability. Ideally, students would also have visited and explored the area they are designing their ecosystem for so they have first hand experience with the environmental conditions they are asking their plants and animals to survive in.

Ecosystem Plan - Getting Ready

Getting Ready

1. Collect lists of local native plants and animals. Set these lists and the field guides in an area that students can access to conduct their research.
2. Make copies of the Ecosystem Plan Assignment Sheet for each group or for each student
3. Set poster making materials out in a place that is accessible to the students

Ecosystem Plan - Lesson Plan

Lesson Plan

1. Open the lesson by reviewing the space the ecosystem will be designed for either through pictures, drawings, or an in-person visit. Consider all the non-living parts of the ecosystem and encourage students to brainstorm the characteristics of the environment that they can remember. How big is it? Is it sunny or shady? Is it warm or cool? How much rainfall does it get? Is it close to any other water resources? What is the soil like? Is it hilly or flat?
2. Tell them that they will be designing an ecosystem to fill this space. Their job is to choose a minimum of 8 plants and 5 animals that could survive in this environment and who would, together, support one another in a food web. In my classes, when I told them that the best designs would be given to our restoration partner and that we would actually be planting many of the plants they chose, the students became totally excited.
3. Ask the students what they would need to consider in choosing their plants and animals. For instance, should you choose all carnivores? Should you choose all trees? This is an ideal time to bring up the concepts of interdependence and biodiversity. Emphasize that the animals and plants will be dependent on each other and their environment so choose carefully so that all the organisms have everything they need to survive. Also, emphasize how greater diversity generally makes an ecosystem more healthy and more sustainable.
4. Once students have a good sense of the assignment and the keys to success, pass out the assignment sheets. Read through the sheets together, highlighting the things they are responsible for doing – making index cards for each species, creating a poster, writing a description of the ecosystem, drawing a map and creating a food web.
5. Divide them into groups, show them where resource materials are, show them where the poster making materials are, and have them get to work. As students work on this project it is critical to continually remind students of the big picture. Is your ecosystem diverse, balanced and sustainable? How do all your organisms fit together in a food web? Does each species have everything it needs to survive in your area? I found that my students became totally engrossed in the individual plants and animals and forgot to consider whether they had the necessary adaptations to survive in the environment – an endangered salamander living near the area where people walk their dogs or a coyote in an urban park setting. Encourage students to choose the most robust and adaptable species rather than the cutest and cuddliest species.
6. When the posters are complete, set aside a day for students to present their designs. Some questions you may want to ask include:

• What are the relationships between the living and non-living parts of your ecosystem?
• How did your group maximize the diversity in the space you were given?
• What challenges arose and how did you overcome the problems?
• What guided you to choose one organism over another?
• How will the presence of humans and their pets affect the ecosystem?
• If your plan is implemented, how hard will it be for our class and future classes to maintain the ecosystem once it is established?

Ecosystem Plan - Sources and Standards

Sources
The idea for this project was adapted from the “Ecosystem Facelift” activity in Project WILD K-12 Curriculum and Activity Guide.

You will need to help give the students a head start by identifying some of the native plants and animals local to your area and the site they are designing their ecosystem for. I used the following resources:
Erica Campos put together a wonderful Creek Care Guide with the names of many local native plants found in riparian corridors.
The Piedmont Avenue Neighborhood Improvement League recently restored an area of the creek we were working on just a mile upstream of our adopted site. They created this listing of native plants that were selected for their project.
Another local creek organization, Friends of Sausal Creek, created this wonderful group of fact sheets about the plant and animal life near their creek. Of particular interest are the Tables of Biological Resources of the Upper Sausal Creek Watershed which lists many of the animals that can be found in and around their creek and the Gardener’s Guide to the Sausal Creek Watershed by Martha E. Lowe which contains detailed information about the many native plants that grow in our area.

In order to find lists of natives in your local area, try contacting nearby environmental organizations, creek groups, neighborhood groups, and local parks. The staff and volunteers at all these organizations are likely to be excited about your work and most will be enthusiastic about helping you gather information.

Standards
Grade 6
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment.

Grade 6
Resources
6. b. Students know different natural energy and material resources, including air, soil, rocks, minerals, petroleum, fresh water, wildlife, and forests, and know how to classify them as renewable or nonrenewable.

Grade 6
Investigation and Experimentation
7. f. Read a topographic map and a geologic map for evidence provided on the maps and construct and interpret a simple scale map.

Grade 7
Investigation and Experimentation
7. d. Construct scale models, maps, and appropriately labeled diagrams to communicate scientific knowledge (e.g., motion of Earth’s plates and cell structure).

TAC Experiment - Logistics

Time
30 minutes to set the stage and brainstorm ideas
20 minutes to propose an experiment (more if you want students to conduct background research on their topic)
20 minutes to set up experiments
10 minutes a day, two to three times a week, for 1 month, to make observations and record results
30 minutes to organize results and draw conclusions
5 minutes per group to present the results to the class
optional: 45-50 minutes to create posters displaying scientific results prior to the presentation

Grouping
Teams of 2-4 students

Materials
Each team needs:

• 2 fully constructed terraqua columns (reuse the ones from the Terraqua Columns lesson or see Bottle Biology building instructions)
• 1 foot wick (1-2 cm wide strip of old cotton towel)
• other materials brought from home, varies for each group depending on the experiment the group wants to try
• copies of the “TAC Experiment Checklist”

Materials for the class to share:

• Soil, either store-bought potting soil or soil from outside
• Hand trowel
• 1 package radish seeds OR Wisconsin Fast Plant seeds
• Water
• Graduated cylinder
• rulers
• pH test strips
• dissolved oxygen test kit (see the Water Analysis lesson - Sources section)  
• pool or aquarium thermometers
• optional: microscope and glass slides

You may want to have on hand for students to use in testing:

• fertilizer
• creek/pond water
• an herbicide like Round-Up
• a weak acid like vinegar

If you wish each team to create a poster to display their results, you should have (or have the students get):

• for each team - 1 piece of posterboard, tri-fold display board, large sheet of cardboard (Costco and other warehouse distributors have lots of cardboard), or even 11x17 sheets of construction paper
• markers
• glue sticks
• scissors

Setting
classroom

TAC Experiment - Background

Teacher Background
Students are most engaged in learning when they can steer the direction of their own learning. In this lesson, students are able to design an original experiment, learn about experimental variables and controls, and present their results to the class. They use their experience with terraqua columns, water quality testing and soil analysis to guide their inquiry in a direction of their choosing.

To get a sense of what students might come up with, these are a few of the experiments my students conducted:

• add soda to the water
• add vinegar to the water
• compact the soil by stomping on it after planting the seeds
• compare a regular column made from 2 liter soda bottles to a tiny column made from 500 ml water bottles
• use a wick made from thick cotton twine rather than a strip of towel
• throw garbage from a school lunch on top of the soil before watering
• use water from the San Francisco Bay versus tap water
• use water from the creek versus tap water
• use garden soil versus school yard soil
• add fertilizer
• add compost
• put one in direct sunlight and the other in shade
• put one outside and one inside the classroom
• add ice to the water each day

A key outcome of this project is a basic understanding of the scientific process and of variables in experiments. While your students may not need to know everything that is outlined below, it is essential that the teacher is solidly grounded in the scientific method and experimental design issues. Pick and choose from the content below to decide how much your students need to know.

The Scientific Method
The scientific method is simply the process scientists use to learn about the world. Generally, the steps are

1. Pose a question.
2. Research as much as possible about that question.
3. Based on that research, come up with a hypothesis (an educated guess).
4. Design and conduct an experiment.
5. Collect observations (your results).
6. Draw conclusions that hopefully answer your question and compare your results to your hypothesis.

For example, in this project, a team might start with the question: “If I spilled a soda, how would that pollution affect the plants, water, and soil in an ecosystem?” They would find out what they know about pollution, urban runoff, and the chemical composition of soda. Finally, they might hypothesize: “Pollution will make the plants grow more slowly or not at all, make the water have a low pH because of the acid in soda, and make the soil have a low pH as well.” They would design an experiment: in one terraqua column, pour a soda into the water chamber and in the other, use plain water. They would measure the height of any plants that grew as well as the pH of the water and soil. Finally, they would look at their results over the month and draw some conclusions.

Variables
One unique element that makes science different than any other discipline is the controlled experiment. In science, we create theories based on evidence, and the evidence must be something that other people can repeat and observe for themselves. Every step of the scientific method centers upon understanding the need to control variables. So what is a variable and what does it mean to control a variable?

A variable is anything that might change in an experiment. Anything that you as the scientist change is a variable (like whether or not to put soda on your plants). Most everything that you measure and observe at the end of an experiment is a variable (like whether or not the plants grow and how tall they grow). And there are often variables that you don't even notice but can affect the experiments (the temperature in the room, how much time has passed, how damp the room is, whether the spoon you are using to measure materials is clean or not). An experiment has three kinds of variables: independent, dependent, and controlled.

The scientist changes the independent variable. In a good experiment there is only one independent variable. As the scientist changes the independent variable, he or she observes what happens. In our example, the independent variable is whether or not the scientist added soda to the water compartment.

The dependent variable is what you measure and want to know about in your results. The dependent variable changes in response to the independent variable. For example, the dependent variable is the height of the plants, the pH of the soil and the pH of the water.

Experiments also have controlled variables. Controlled variables are quantities that a scientist wants to remain constant, and he must observe them just as carefully as the dependent variables. For example, if we want to measure the difference in the height of plants in soda versus water, it is essential that we use the same kind of seeds in both terraqua columns. If we use radish seeds in one column and carrot seeds in the other, we can't be sure if the carrot seeds with soda grew more slowly because of the soda or because carrot seeds normally grow more slowly than radish seeds. Similarly, we want to make sure that they get the same amount of light, that they have the same type of soil to grow in, and that they stay the same temperature.

In a controlled experiment the scientist has considered all 3 types of variables. She tests a hypothesis by changing the independent variable and noting the effect on the dependent variables, all the while making sure that controlled variables stay the same. Good experiments make it so that the only difference between the control group and the experimental group is the independent variable.

Experimental and Control Groups
In many experiments, such as these terraqua column experiments, the scientist makes a comparison between different groups. The group that does not receive any treatments - the one where the independent variable is not changed - is called the control group. For example, a plant with no fertilizer.  The group or groups that do receive a treatment - the ones where the independent variable is changed - is called the experimental group. It is essential to have a control group in these types of experiments or you will not be able to determine if a plant that got a treatment is any different.

When all of these details are taken care of, and when a difference in the dependent variable exists, then the experimenter can say it was the independent variable that caused the difference. There have been plenty of bad experiments in the real world. So, a smart scientist (and a good students) will look to see exactly how the experiment was designed and conducted in order to determine if the conclusion drawn from the data is really true.

Student Prerequisites
Student should have:

1. Built and observed a terraqua column (see Terraqua Column lesson)
2. Tested water quality (see Water Analysis lesson)
3. Tested soil (see Soil Analysis lesson)

TAC Experiment - Getting Ready

Getting Ready

1. Make copies of the “TAC Experiment Checklist”, either to hand out to each student or to display as an overhead.

Setting up the experiments

1. Have your students empty out their old terraqua columns and rise the containers
2. Prepare new wicks (1-2 cm wide strip of old cotton towel)
3. Set out soil, hand trowels, seeds and graduated cylinders
4. At this point, you should have an idea of what each group intends to do. Make sure that each group has the materials they need OR provide the materials for them.

Making observations and recording results

1. Each day you plan to make observations, have pH paper, rulers, dissolved oxygen test kits, and thermometers available
2. Optional: set out microscope(s) and glass slides

Presenting the results

1. Optional: set out poster making supplies – posterboard, markers, scissors, and glue sticks

TAC Experiment - Lesson Plan

Lesson Plan
Brainstorming, researching and proposing an experiment

1. Have your students take out a sheet of paper and fold it in half vertically.
2. Title one half “Things that might help the mini-ecosystem in my terraqua column”. Title the other half “Things that might hurt the mini-ecosystem in my terraqua column”. Divide the board into two columns as well.
3. Give students 3-5 minutes to come up with ideas for each side of their paper. For now, allow students to interpret “help” and “hurt” in any way they want. If students are having difficulty thinking of ideas, ask questions like:
   • What do people do that is good for the environment in general?
   • What do people do that is bad for the environment in general?
4. When 5 minutes have passed, ask students to share their ideas with you. Write their ideas up on the board as they are suggested. One effective way to do this is to go around the room and have each student share one idea before opening it up to anyone to share a second or third idea. It is likely that different students interpreted the question differently – some might think about re-engineering the terraqua column while others might think about ways to help the plants grow better. This is GREAT! You can draw attention to these different interpretations as they appear.
5. Tell students that they will now have a chance to change one thing about their terraqua column and compare the changed column to one without the change. Using the ideas on the board, go through a couple examples of things that they might want to change.
6. Emphasize the importance of having two columns, one to make a change in and one without the change to compare the other one to. For instance, consider an imaginary student Bill who wants to know how adding fertilizer might affect the plants. He builds a terraqua column and adds fertilizer. The plants grow to be 20 centimeters tall. Can Bill conclude that the fertilizer made the plants grow taller? No! Taller than what? Without a column that was the same in every way except that it didn’t get fertilizer, Bill doesn’t have anything to compare the 20 centimeter plants against. If you want to introduce the associated vocabulary (experimental group, control group) then do so here.
7. Emphasize the importance of changing only one thing. Lead students through several example experiments where several variables were altered simultaneously. For instance, think about Bill and his fertilizer experiment. Bill also thinks that garden soil is probably better for plants than school yard soil. So, in one column he plants seeds in garden soil and uses fertilizer. In the other column he plants seeds in school year soil and no fertilizer. In the end, the plants in garden soil and fertilizer grew taller. Can Bill conclude that the fertilizer made the plants grow taller? No! Maybe the garden soil made them grow taller. You can’t tell which variable caused the plants to grow taller if you change more than one variable at a time! If you want to introduce the associated vocabulary (independent variable, dependent variable, and controlled variable) then do so here.
8. Divide the kids into their teams. Tell them to design an experiment with their terraqua columns. In their lab notebooks, have them write out their idea in words and also draw a picture of the two columns illustrating what they plan to do. Circulate around the room to help groups who are having trouble settling on a single thing to change.
9. Once most groups have an idea of what they want to do, ask students to predict the differences between the plants, water and soil in the two columns. These predictions should be as specific as possible. “The plants will grow better” is not enough. Aim for details such as “the plants in the column with fertilizer will sprout earlier, will be taller, and will have more leaves than the plants without fertilizer.” The end goal is for students to choose 3-4 things they can measure over the next month. Again, circulate around the room to help groups make predictions and choose 3-4 dependent variables to measure.
10. Before students turn in their experiment designs, make sure they all have the following 4 things written down:
    • The idea behind the experiment in words
    • A labeled picture of the two columns they plan to build
    • Predictions of the differences between the plants, water and soil in the two columns
    • A list of 3-4 measurements they plan to make 2-3 times a week for the next month
11. When they are finished, have them turn in the experiment design to you for approval before they can actually do it. Depending on your students, you may need to go through several rounds of revisions before they have an acceptable experiment designed.

Setting up the experiments

1. Make sure that all teams have a well designed experiment and have all the materials they need.
2. Give students at least 20 minutes to build their columns and make their initial observations.

Making observations and recording results

1. 2-3 times a week for the next month, students need an opportunity to make observations of their columns. Each time, they should make the same set of 3-4 measurements in both columns. You may wish to conduct periodic checks of their lab notebooks to ensure that the date of each observation and all the data is being recorded.

Organizing and presenting the results

1. At this point, students should have 8-12 observations for each of the dependent variables the students chose. There should be a lot of data. The first task is for each group to go through their lab notebooks to organize the data and look for patterns. The best way is generally to create a table like the one below for each type of measurement that was made:

   pH of the water
   Date	Column with fertilizer	Column without fertilizer

   I showed students 2 examples of how to create tables of their data (picking the types of measurements most common within the class – height of any plants and water pH) then let them get started.

2. Next, students should look for patterns in each table. Often, graphing the data (if it is numerical) helps. The younger students may have difficulty graphing and may need more instruction about how to set up the axes of the graph and how to plot the data.
3. Finally, have students summarize any other observations that weren’t on the original list of planned dependent variables. For example, “On 11/18/04 the column with fertilizer tipped over and all the soil and water spilled out.” Or “On 11/30/04 fuzzy white mold appeared on the surface of the soil in the column without fertilizer.”
4. Have students draw conclusions. The questions I asked my students were:
   • Go back and read the idea behind your experiment. Then look at the patterns you observed. What did you discover? Use your measurements and observations to describe how the terraqua columns were affected by the change you made.
   • Go back to your predictions. Use your measurements and observations to explain why your hypothesis was right, wrong, or why you cannot tell.
   • What you would do differently if you were to do this experiment again?

   Naturally, you can create different questions or reword them to suit your own classroom.

5. Finally, have students share their experiments with the class. This may be done orally or through a “poster session”. If you wish to have your students create posters, it is helpful to create one of your own with fake data so that they have an idea of what is expected. Once the posters are made, they can present their posters to the class.

TAC Experiment - Sources and Standards

Sources
Bottle Biology contains everything you wanted to know about terraqua columns.

Standards
Grade 6
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:

Investigation and Experimentation
Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:

Grade 6
a. Develop a hypothesis.
b. Select and use appropriate tools and technology (including calculators, computers, balances, spring scales, microscopes, and binoculars) to perform tests, collect data, and display data.
c. Construct appropriate graphs from data and develop qualitative statements about the relationships between variables.
d. Communicate the steps and results from an investigation in written reports and oral presentations.
e. Recognize whether evidence is consistent with a proposed explanation.

Grade 7
a. Select and use appropriate tools and technology (including calculators, computers, balances, spring scales, microscopes, and binoculars) to perform tests, collect data, and display data.
e. Communicate the steps and results from an investigation in written reports and oral presentations.

Grade 8
a. Plan and conduct a scientific investigation to test a hypothesis.
b. Evaluate the accuracy and reproducibility of data.
c. Distinguish between variable and controlled parameters in a test.
e. Construct appropriate graphs from data and develop quantitative statements about the relationships between variables.

Rotten Log Lab - Logistics

Time
45-55 minutes

Grouping
Groups of 4-6 students per log

Materials
For each student:

• Copy of the Rotten Log Questions

For each group of students:

• 1 rotting log, preferably with lots of mushrooms, moss, fungi, termites, beetles and other creepy crawlies in and around the log
• 1 large plastic wash basin or large heavy duty yard waste trash bag to keep the log in
• Work gloves
• Screwdriver, shovel, pry bar, hammer or other tools that can be used to pry open sections of the log
• Bug boxes
• Newspaper to cover the tables

Optional: To see the protozoa in the termites’ gut

• Termite
• Microscope
• Glass slides
• Cover slips
• 2 pairs tweezers
• toothpick
• 0.6% NaCl (0.6 g NaCl in 100 ml water)
• eyedropper

Setting
Classroom

Rotten Log Lab - Background

Teacher Background
I used this activity as a lab-based test that the kids didn’t actually think was a test. It was a super way for them to reveal the holes in their understanding before the written test. Some of the major concepts that can be assessed in this lab include differentiating between a community and an ecosystem, creating food webs, identifying interactions between organisms and between organisms and their environment, predicting the effects of human impact on populations, and assessing ecosystem sustainability.

In addition, I was able to show them an amazing symbiotic relationship between termites and protozoa. Termites eat wood but cannot completely digest the wood on their own. Many varieties of protozoa, single celled animals with amazingly varied modes of locomotion, live in the termites hindgut and help digest the cellulose in the wood. They attach themselves to the inner wall of the termite’s gut to keep from being excreted with undigested wood particles. In return for their invaluable services, the protozoa get a nice, safe home and a constant supply of food.

Student Prerequisites
Knowledge of food webs, ecosystems, organism-environment interdependence, and sustainability.

Rotten Log Lab - Getting Ready

Getting Ready

1. Find some nice, juicy, moss and mushroom covered, termite and beetle infested logs. You know you’ve found a good log if you can pull off chunks of wood with your hands. I discovered mine (8 logs, enough for my students in groups of 4) in a wooded area of Golden Gate Park. You can use the same log with 2 successive groups of students if you just make sure the first group doesn’t go crazy with the hammer. You can also flip the log over for the second group. I found that the best time to go log hunting is after a month of nice, wet weather after mushrooms have begun to appear.
2. Make copies of the Rotten Log Questions
3. Cover your tables with newspaper
4. Set out logs and the group materials

Optional: Set up protozoa viewing station. I would practice extracting protozoa on your own first. The protozoa are active for around 2 hours before they stop moving so you’ll need to set up a new slide every few hours.

1. To extract the protozoa, first find a termite and put it on a glass slide. Use one pair of tweezers to hold its head and the other to hold its rear. Slowly and firmly pull apart. You should see a long, stringy tube, the hindgut. If you don’t squeeze the rear end with the tweezers until you do.
2. Place a drop of saline on the hindgut and mash the hindgut with the tweezers or a toothpick. If the hindgut never came out at all, you can mash the entire rear end.
3. Cover with a coverslip.
4. Observe under the microscope. Look for a mass of writhing stuff. You should be able to zoom in and observe individual protozoa and see differences between the many species that are present.

Rotten Log Lab - Lesson Plan

Lesson Plan

1. It’s pretty useless trying to hold the kids attention when there are moss and mushroom covered logs on the tables. Thus, give the students the question sheet right away and let them go once you read the rules:
2. Use any of the tools provided.
3. Don’t harm any organisms.
4. You may carefully break small pieces of the log apart but NO SMASHING. Keep all the pieces of the log in the basin, NOT all over the table or the floor.
5. Have students answer the questions in a lab notebook or on a separate sheet of paper. The questions are on the student Rotten Log Questions download but are also listed again here for your convenience:

• List as many organisms in the ecosystem as you can find. For each organism, draw a picture and label it with a name that describes the organism like “light-brown, long bodied ant-like thing” or “2 cm-long black beetle”. More things are living than you might think…
• List as many non-living parts of the environment as you can find. There is more than just wood – think about solids, liquids AND gases!
• Which of the things you just listed are part of the log community?
• Which of the things you just listed are part of the log ecosystem?
• What is the difference between a community and an ecosystem?
• Find evidence about the food webs that make up the community. Do you see any organisms eating? Do you see any “poop” that gives a hint about what the organisms have been eating? Draw as much of the food web as you can.
• Describe one organism-organism interaction that you observe.
• Describe one organism-environment interaction that you observe.
• How will this lab impact the populations of organisms in your log? Pick one organism and describe how the population of this species will be affected by our investigation.
• Is this ecosystem sustainable? Why or why not? Use your observations to support your idea.
• If you have a protozoa viewing station set up, invite groups one at a time to come visit you at the microscope to see the protozoa.
• Reserve plenty of time to clean up.

Rotten Log Lab - Going Further

Going Further
Another cool termite trick… Did you know that termites mistake the smell of a Bic pen for a pheromone that they use to navigate? Pheromones are chemicals that communicates a message to other members of the same species. Although humans do have pheromones, termites and other social insects communicate extensively through these chemical messages. Termite workers indicate the path to a food source by leaving behind a trail-pheromone. A chemical in Bic pens (not other pens for some reason) mimics the trail-pheromone. If you draw a line with a Bic pen on paper then place a termite on the line, the termite will faithfully follow the line wherever it leads. Try drawing curly-Qs and other shapes. See what happens when a termite hits a crossroads. Try pens by other manufacturers. Try different colors of Bic pen.

Rotten Log Lab - Sources and Standards

Sources
The idea for this activity came from a workshop by Karen Kalamuck at the Exploratorium. THANK YOU Karen!

If you just can’t be bothered to go find rotting logs but really want to try the termite activities, termites can be ordered from Carolina Biological with instructions for how to isolate the protozoa ($11.25) OR with instructions for how to draw lines with Bic pens ($32.75).

Standards
Grade 6
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment.

All Grades
Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations.