Lewis/Life - Teaching Techniques

Chapter 42 - Teaching Techniques

A. General Tips
Chapters 41 - 44 deal with problems for which there are no simple solutions. Your students, however, will be looking for simple solutions. Be on guard for simplistic approaches to complex situations. Play devil's advocate liberally throughout this material.
Point out that one of the nice things about ecology is that the terminology is almost always exactly what it sounds like. There are no really new terms.
You might wish to copy and distribute to your students the Overview of Chapter Objectives flowchart found at the beginning of this Instructor's Manual Chapter.
B. Possible Approaches to the Chapter
At the end of this chapter I have included a short essay by a colleague in Taiwan. Although Dr. Lee wrote this as a laboratory exercise, I encourage you to adopt what she wrote and use parts of it even if your course does not include a laboratory component. Students often look for ecosystems "out there somewhere" instead of right at their feet.
Another "personal ecology" project that can be done, even in the absence of a laboratory, is a diary of a plot of land. Set your own parameters: time frame (usually several weeks), size of plot (usually under 6 ft x 6 ft), what the students should be looking for, what else will be required. Each person should work alone and watch what happens to the various components of the ecosystem. Most students get a great deal out of this type of project.
C. Hints Related to Specific Chapter Topics
- I. The spiral pattern formed when the blue whale swirls the krill really does look like a vortex. If your students do not know what a vortex is, describe it or demonstrate a vortex.
- II. One of the biggest problems is defining the limits of a community. You might ask where one community ends and the next community begins. This has to do with community interaction.
  Another problem is that we use the term community rather loosely. For instance, we talk about small, bustling communities found in rotting tree stumps and we talk about vast communities traversing the Great Plains. For most of us, the shift in the usage of the word community is no particular problem. Occasionally a student needs to be reminded.
- III.C. Lewis brings out the problem of identifying and defining climax communities. Some of your students may have learned that the climax community is an absolute. The thinking on this is changing. Ask the class what factors might prevent a community from reaching the classical definition of a climax community.
- IV. I invite you to discover with your students your own ecosystem. See Dr. Shu-wen Lee's essay at the end of this chapter.
- IV.C. I suggest you sketch the pyramids as you discuss them. The energy pyramid will be rather uniform. Show how the pyramid of numbers can be quite variable. Ask why. The pyramid of biomass can also be highly variable. Again, sketch this out and ask why.
- V. One of the best ways to teach the biogeochemical cycles is by using the diagrams, Figures 42.12 through 42.15.
- V.C. If you are going to spend any time with the nitrogen cycle, you may have to review a bit of the chemistry. Explain the difference between nitrate, nitrite, nitrogen gas, nitrogen oxides, and ammonia. Keep it simple.
- VI.A. Stress Figure 42.16.