Topic: Marine Ecology
Grade Level: 6-12
Summary: Students will lay out transect lines beside a local stream or river. There they will record species of plants and insects living around the stream. By doing so, students will learn how to use transect sampling techniques, use a variety of methods to sample species, and compare species diversity and density between parallel transects.
Introduction: Posing an intriguing problem often helps draw students toward learning the abstract concepts involved. Here is an easily modeled situation which will generate many questions and explanations.
What to Expect: As always when using water, prepare surfaces for splashes and spills.
Materials: Provide each group with a clear, waterproof box about the size of a shoebox containing:
- Centimeter ruler
- Wax pencil
- Butter tubs
- Pennies, rocks or fishing weights
- Aluminum foil
- Clay
Procedure:
1. Hand out the problem: Imagine a staysail schooner loaded with mid-ocean ridge basalt as it floats in a swimming pool in Woods Hole. If all the basalt is dumped over the side into the pool, will the water level of the pool rise, fall, or stay the same?
2. Generate discussion about what will happen. Words like density, Archimedes, volume, and buoyancy will probably come up. Write these concepts on the board as they come up, aiming for clarity.
3. Divide students into small groups or pairs according to what they think will happen: the risers, the fallers, and the stay-the-samers.
4. Send students into the lab with their boxes to find the answer. Instruct the students to design their own lab investigation, using only the materials in the box (though not necessarily all of them). Students should document all procedures they follow in their lab.
5. Have students present their methods, results, and conclusions to the class. Students should be prepared to defend their reasoning and conclusions.
Evaluation: Students will write up lab results in standard form and write in their journals about this experience.
Extensions:
1. Have students find out about the scientific and engineering contributions of Archimedes.
2. This exercise works well with units on density, boat design and displacement, and properties of water.
Copyright 1998-2008 by Sea Education Association, all rights reserved. Compiled and edited by Pat Harcourt & Bill Meyer.
This project was supported, in part, by the National Science Foundation (Proposals # TEI-8652383, TPE-8955214, and ESI-925324), the Henry L. and Grace Doherty Foundation, the Donner Foundation and the Pew Charitable Trusts. Opinions, findings, conclusions or recommendations expressed are those of the authors and not necessarily of the Foundations.
