Science as inquiry
Variation in a population is the raw material on which natural selection works. How do scientists measure and quantify variation in traits? We use garden snails as a model organism in order to describe and measure several different traits. Groups are given a small population of snails and must devise an objective way to measure a trait of their choosing (length, mass, speed, color intensity, stripes, withdrawal reflex reaction time, number of pennies it can carry, etc.). There are many ways to extend this activity. For instance, scientific protocols may be traded between groups, hypotheses may be made concerning what individuals will survive better in different environments, and snails may be tagged and released into one or more environments and the populations monitored over time. A long term open-ended project such as this provides a natural extension and assessment opportunity for both evolution and ecology concepts.
Submitted by irene on Thu, 2006-07-13 21:13.
Cartoon by Chris Madden
What caused the extinction of the dinosaurs? Was it a massive meteor? Was it the result of tremendous volcanic activity that covered the globe in volcanic ash? Was it the effects of gradual climate change? Was it the result of plate tectonics? Students are given a set of evidence cards that state scientific discoveries about rocks from 65 million years ago and prediction cards that discuss the predicted effects of different events such as a meteor impact, a rise in carbon dioxide levels, and plate tectonics. Teams of students are charged with assembling this information into an overarching theory that best explains the evidence at hand. At the end of the period or the following period, teams present their theories to the whole group and enter into a debate about the cause or causes of the great dinosaur extinction.
Can sort through evidence and come up with a scientific theory that best fits the data.
Can recognize whether evidence is consistent with a scientific theory.
Can use geologic evidence to propose theories about past life on earth.
Submitted by irene on Sun, 2006-03-26 12:03.
To apply students’ understanding of the rock cycle and basic principles of stratigraphy, I brought my students to the Caldecott Tunnel to investigate the local geology and piece together the geologic history of their backyard. The east side of the tunnel has an easily accessed road cut that displays a gorgeous example of a contact between older sedimentary rock layers and a more recent volcanic layer. The whole thing has been folded and faulted by the actions of the Hayward Fault, and thus the layers are no longer horizontal but at a sharp diagonal. My students drew pictures of the northern cliff face on the Orinda side of the tunnel then each student was assigned a rock layer to study in detail. When we got back to the classroom, we reassembled the data on the whiteboard, and made theories about the sequence of events that would bring about the rock layers we observed in the cliff. Finally, students drew pictures of what the area must have looked like at different parts of the timeline. This field trip led gracefully into the next segment of the unit on geologic time.
Photograph of the northern roadcut face at the Caldecott Tunnel from the field trip “Caldecott Tunnel between Oakland and Orinda” by Russell W. Graymer in "The Geology and Natural History of the San Francisco Bay Area: A Field-Trip Guidebook", edited by Philip W. Stoffer and Leslie C. Gordon.
Submitted by irene on Mon, 2006-02-27 19:13.
Every rock holds clues about how it formed. Geologists are like rock detectives who know how to read the clues about a rock’s origins and the stories it can tell. In this activity, students first become specialists in one type of rock. Then, they meet specialists in other rock types to compare their rocks and teach the others about their rock’s history. This lesson is an opportunity for students to consolidate information from the previous lesson on the rock cycle, and begin to think like geologists. Ideally, the rocks selected for investigation are collected from the site of an upcoming geology field trip – such as to the Caldecott Tunnel or Mount Diablo. In this way, students gain experience identifying individual rocks and learning about the way in which each of the different rock types form. Then, on the field trip, students can apply their controlled classroom knowledge to real world geological history.
Submitted by irene on Fri, 2006-02-24 21:53.
Once students have some experience working with a basic terraqua column (see the Terraqua Columns Lesson), they have an opportunity to design and conduct their own investigations with their mini-ecosystems. There are hundreds of variables students can manipulate with a minimum of materials – temperature, light, pollution, type of water, type of soil, etc. As a class, students brainstorm variables that might affect the plants, soil, and/or water in a terraqua column. In teams, students propose a project, and once approved, set about testing their ideas and observing the effects of their manipulations on their mini-ecosystem. If your school participates in a local science fair, this is a fantastic activity to introduce students to experimental design, variables, and control groups.
Submitted by irene on Sun, 2006-01-29 20:37.
In this culminating project, students go out into the field and test their theories about erosion and sedimentation at a local creek. How are sediments distributed along the creek? Does it vary by location (the source, mid-stream, and the mouth)? Does it vary by the velocity of the current? Different classes can collect information for the different study areas. At a study site, they will draw maps, measure the velocity of the current, and collect sediment samples from the creek bed. These samples are analysed back in the classroom for the percent of different sediments they contain. Finally, students stand back and examine their data to try to make sense of the sediments they find. If it is not possible to bring students to a creek, there are many ways to bring the data to them. Collect the sediment samples yourself with photos and water velocity information OR use the Suspended Sediment Database to draw your conclusions. This USGS database provides stream flow and sediment information for over 1,500 rivers and creeks nationwide (see the Going Further section for more information on using the USGS’s database).
Submitted by irene on Tue, 2005-12-06 22:34.
This section will give you information to help you plan a field trip with Save the Bay. I brought 32 students to Arrowhead Marsh, a hidden wetland near the Oakland Airport, to meet up with extraordinary Save the Bay Instructors. The day was divided into two parts: 1) Canoeing – where we did water quality monitoring, explored the marsh with all our senses, and went on a wildlife scavenger hunt 2) Restoration – where we repotted 300 native plants, cleaned up the shoreline, and went for a walk on a boardwalk above the marsh. Students were able to explore a wetland up close and observe a leopard shark, feel the Bay’s muddy bottom, and listen to the endangered snowy plover.
Submitted by irene on Mon, 2005-11-21 16:23.
In this activity, students finally get to apply their skills of soil analysis and observation to a 1 meter by 1 meter area of the schoolyard, restoration site, or creek bank. Teams of students get down and dirty exploring the soil, vegetation, and insect life in their microhabitat. Students practice using the soil analysis tools they learned previously and also practice using field guides to identify plants and insects. Upon returning to the classroom, they compare their results with other groups to see the differences and similarities between their microhabitats. This is a superb activity to use before and after a habitat restoration project or simply to track changes in a habitat throughout the year. I used this investigation to introduce the idea of native vs. non-native species and to begin a debate about invasive species. My students really “got it” when they examined our adopted restoration area and discovered that there was a monoculture of invasive, non-native English ivy all across our site. They visited our adopted site 3-4 times throughout the year pulling ivy and planting native plants. When all was said and done, they repeated this investigation in the spring to discover exactly the magnitude of the change they made on the environment – and to find that the native plants recruited a wider variety of insects than they had seen at that site in the fall.
Submitted by irene on Wed, 2005-09-28 10:29.
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.
Submitted by irene on Thu, 2005-07-21 15:11.
Students conduct 3 tests of water quality in the classroom that can then be applied to their terraqua columns and to the outdoors: pH, dissolved oxygen, and temperature. They make comparisons between different types of water and draw conclusions about how "healthy" each water source is for fish and other organisms. Through this process, students practice their observational and data analysis skills. Water quality monitoring data is routinely used in the "real world" to determine the effects of habitat restoration, development, pollution, and wastewater treatment. It is often the initial step in describing the health of an ecosystem. There are hundreds of ways to extend this simple activity and make connections to the real world - from monitoring water quality in a local creek to making comparisons between different bodies of water in your area.
Submitted by irene on Wed, 2005-07-20 10:05.