Lewis/Life - Teaching Techniques

Chapter 25 - Teaching Techniques

A. General Tips
Plants are the neglected members of many biology courses today. Your students might well be suffering from "plant deprivation." You probably want to give your students a well rounded biological background but you keep wondering how much botany you really want to cover. I offer the following plan:
If you are a botanist, recall what excited you about the plants. Make a list of those things because those are the points that should be emphasized to your students. If you were confused as a botany student, make a list of those areas you had trouble with. Your students will have the same problems. Now go to your course objectives. What points do you want your students to know about botany and why do you want them to know those points? How do the "excitement points" on your first list correspond with the "confusion points" and the "course objectives" points? If you can blend those three lists into a series of concepts that you are comfortable with, and if you can convey to your students your sense of botanical excitement, you will have put together a very good botany unit.
If you are not a botanist, recall for yourself what you didn't especially like about botany. Make a list of those points. Are these points you should avoid in this introductory course? Are these points you should approach from a different angle? Now make a list of those points that did excite you about botany. And return to your course objectives. What do your students need to know? Mesh your lists. Now you are ready to prepare your plant unit.
If you are not a botanist, encourage your plant-oriented students to do some plant research. It will add prospective both for you and for the students. You may learn something exciting.
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
** You may wish to give just the briefest overview of this chapter now and hold the chapter proper until you get into the next unit on plants.
This is an overview chapter. Do not let it become just a "fact grab-bag." Work from the anecdotes and use plenty of pictures. Make this overview a real botanical experience for your students.
This is a good chapter for a non-quiz. You might include such questions as:
- 1) What is a plant?
- 2) What are the major characteristics of a plant?
- 3) What are some common plant categories?
- 4) What adaptations are necessary for plants to survive on land?
- 5) What are some of the strategies plants use to conserve water?
- 6) Why have flowering plants been so successful?
Your students will probably have difficulty answering these questions completely. Nevertheless, these questions can form the springboard for your discussion on plants.
I strongly suggest you write a basic plant chart. The one following is similar to the ones in the text.
- -- PLANTS --
  - I. Avascular plants (Bryophytes)
  - II. Vascular plants
    - A. Seedless
    - B. Seed bearing
      - 1. Gymnosperms (naked seeds)
      - 2. Angiosperms (flowering plants)
The advantage a simple outline such as this has is that the student can see the phylogenetic progression of these different types of plants.
One of the major themes of this chapter should be the acquisition and conservation of water. As you work through this material, continuously show how the organisms obtain and conserve water. For discussion you might ask the question, "Are all organisms really aquatic organisms, but some just happen to live on land?" (This question could, of course, extend to humans.)
Follow this need for water from the protected environment of the bryophyte, through the development of the vascular system, and on to the benefits of both the naked and the protected seed.
C. Hints Related to Specific Chapter Topics
- I. Note that this section is an expansion of the previous chapter.
- II. Lewis states that true plants are nearly absent in the oceans. This does not just mean mid-ocean. Challenge your students to find out why.
  This section states that at the most fundamental level, plants can be classified by whether or not they have vessels. This is a classic and long standing distinction. Ask your students why having vessels is important.
- III. Some of your students will not understand bryophyte sexual reproduction. Know in your own mind exactly what you will require of your students. Personally, I suggest if you are teaching non-majors, that you keep the intricacies of bryophyte reproduction to a minimum.
  In Chapter 28 of this Instructor's Manual, I have included a generalized life cycle that can be used for any sexually reproducing organism.
- III.A. The most important thing you can impart to your students in this section is an appreciation for the bryophytes. They have been around for a long time; they are well-adapted to wherever they are; they are survivors. Use the anecdotes liberally.
  Some phylogenists disagree with the classification scheme given here and some of your students may have learned another delineation. Use that as an opportunity to show the flux of taxonomy.
- III.A.1. Point out the last paragraph on page 439. Ask your students why all these various organisms that are called mosses are not really mosses at all.
- IV. & V. Throughout these sections stress the evolutionary advantages of each succeeding step. Keep in mind, however, that the organisms lower on the evolutionary scale, are not necessarily "inferior" organisms. After all, they have been around longer than the "more advanced" organisms!
- IV.B. Stress the anecdotes.
- IV.B.4. Invite your students to bring in fronds from their own ferns. Ask them to be especially aware of any with very visible sori. The physical characteristics of the sori are species specific.
  If you have a projecting microscope, use it to show the class the fronds, sori, or other fern structures.
- V. Throughout this section be aware of opportunities to show the class seed plant structures, either by passing items around the room or by using your projecting microscope.
- V.A. Notice here the reference to seed plants not requiring water for the sperm to swim to the egg. Stress this point as a major evolutionary leap. If you are using water as a theme for this chapter, this is another major point where water plays a role.
- V.A.1. On page 499 Lewis states, "Conifers have a second type of leaf. These are narrow and do not occur in fascicles." If you need a bonus point to throw out to the students, ask them to follow up on this idea.
- V.A.2. Stress the anecdotal information about the uses of the gymnosperms.
- V.B. The statement is made that angiosperms are the dominant plant group on the planet. Ask the students why this is so.
- V.B.2. The in-text questions on page 503 are excellent for discussion.
  Another question that is imperative for this section deals with how the great population crashes (regardless of cause) set the stage for angiosperm diversity.
- VII. This section is both interesting and practical. It is also the basis of several points of controversy.