4. Pond Water

Summary

Delve into a micro-habitat that is the size of a drop of water. This lesson allows students to explore the plankton (organisms that drift with the currents) that exist in a drop of pond, lake, or bay water. A microscope is required to view most organisms although some are observable with a hand lens. If possible, this is a fantastic opportunity for students to collect the pond water themselves using pantyhose and a small bottle. If you are pursuing a restoration project, collecting water might be an excellent excuse for an initial visit (as long as the creek/body of water has regions of relative calm where algae can grow on the rocks). Plans for both an initial creek visit activity and a classroom investigation of the water sample are included in this lesson plan. If it is not possible to bring students to the creek or pond, then you can collect the sample ahead of time and skip the creek visit and sense of place activity.

Plankton photo by Jerry Prexioso. From NOAA

Objectives

Creek visit:
Develop a sense of place.

Pond water investigation:
Can define organism, habitat and microhabitat.
Can identify organisms using a key or field guide.
Can use a microscope.

Vocabulary

Plankton
Organism
Habitat
Microhabitat
Microscope
Objective lens
Stage
Eyepiece
Arm
Focus (fine and coarse)

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.