Lewis/Life - Teaching Techniques

Chapter 41 - Teaching Techniques

A. General Tips
This chapter is interesting in that part of it seems to include material that everyone knows about but no one really seems able to define and another part of it includes projections that no one can address definitively. Thus, this chapter leaves a great deal of room for the very appropriate behaviors of thinking and speculating.
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.
Most students believe (in practice, if not in theory) that ecology means, "We've gotta save everything!" Your task will be to explore the depths of interactions as well as the delicate ecological balance that exists in the natural world.
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
Probably the best way to begin this chapter is with a non-quiz. Ask for some simple definitions such as ecology, niche, habitat, population, and carrying capacity. Then pose a population problem such as what is happening in China. Ask the students to formulate a solution. Or ask if hunting should be outlawed. There are very few definite answers with a non-quiz such as this. (Even the definitions are not universally agreed upon!) But, you will have started the students thinking.
C. Hints Related to Specific Chapter Topics
- I. This two paragraph section should be mandatory reading for everyone. Then ask what we should do. Should municipalities allow the animals to starve or should there be controlled hunting? Almost every state in this country faces deer population problems right now. When deer are allowed to roam free and hunting is restricted, the deer destroy the human food crops. Yes, they usually have plenty to eat, but at what cost? And, if the deer are kept out of the farmers' fields, they starve. Of course, there is no easy answer to this problem; but it is certainly worth becoming concerned about.
- III. The most important point you can make about habitats and niches is that each organism occupies a unique place in the total scheme of things. Just as in physics (where we learn that two objects cannot occupy the same place at the same time), so too in ecology we learn that each organism -- as well as each species, population, etc. -- must have its own place and its own resources. Sometimes it can adapt; sometimes it cannot.
- IV. The information in this short section is straight logic. You might simply assign it.
- V. This entire section should either be covered or not covered. It does not "skim over" very well.
- VI. Consider this entire section in view of your course objectives. How much of this do you really want your students to know? Every student should know three terms from this section: carrying capacity, density-independent factors, and density-dependent factors. The logistic growth curve (section VI.C) and K-selection versus r-selection (section VI.E) will be confusing to many of the students.
- VII.A. The principle of competitive exclusion is simply an extension of what was said in section III above. Most students will see this as amazingly logical.
- VII.B. Most students will find predator-prey interactions to be quite interesting. Some will find it a bit disconcerting. In a world where everything is supposed to be ecologically sound and politically correct, it is hard to imagine a natural system of checks and balances that deliberately causes the death of other living organisms.