Lewis/Life - Teaching Techniques

Chapter 17 - Teaching Techniques

A. General Tips
This is an interesting chapter and your students will basically like it.
One problem that invariably comes up, though, is the concern that certain Fundamentalist Christians have about evolution. I encourage you to respect these concerns and to help the students understand that they may actually be coming at evolution from a false premise.
Biology in Action - 17.1 deals with the "chiral" concept. Students who have had a good chemistry course in the past, whether high school or college, will probably have learned about chirality. If you are trying to streamline your course, this topic could be omitted from your main discussion, but I would suggest you ask your students to read through the section for their own enrichment.
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
If you want a real eye-opener, begin this chapter by asking your students to write down a definition of evolution. The vast majority, even if they are coming to you with a good high school background, will not have the foggiest notion about what evolution is. The stock answer is that man came from the ape. So many do not see the relationship between evolution and speciation, even if they have heard it a thousand times.
You might also ask them to write down whether or not they think trees evolve. To many of the students, evolution involves only humans; plants don't even fit into their evolutionary scheme. This is a very difficult mind-set to overcome.
The material in this chapter -- actually in the whole unit -- lends itself well to the annotated outline. Such an outline could be assigned to be handed in before you lecture on the material. That way the students would have a perception of the sequence of events under consideration and the lecture itself could be used to focus on a conceptual or developmental understanding of the information (rather than on a straight chronology).
Use the "clock" on page 360 and the chart on pages 362 and 363 as focal points for your lecture.
As you teach this chapter, try to build a sense of excitement and wonderment.
Much of what is covered in this chapter is speculation. Some of the students may become skeptical because of the many "possibles" and "may have beens" presented here. Work with this by stressing that that is how science works. We are just at the starting point on so many of these ideas. So, as per the Scientific Method, we offer a suggestion and then we attempt to prove or disprove it. And then we move on. That is where we are right now with many of our ideas of the early history of life on this planet. We have some ideas and we are trying to go from there.
C. Hints Related to Specific Chapter Topics
- II.B. Be sure to mention the Mars rover.
  An interesting point here is whether or not spores could survive exposure to radiation in space. New research is suggesting that if the spores were embedded in something, perhaps they could survive. Bacteria embedded on sealed fossils for millions of years have been rejuvenated. (See also "Additional Topics" question # 2.)
- II.C.2. Ask the students to recall the definitions of hydrolysis and dehydration synthesis. Some will have forgotten.
- III. Work from Figure 17.7; it is an excellent synopsis of this material. You may have to give a brief demonstration of what "reverse transcriptase" is.
  Retroviruses are mentioned in this section. You might want to remind the class that HIV is a retrovirus.
- IV. Note the opening line, "Metabolism is the ability of organisms to acquire and use energy to maintain the organization necessary for life." This is an excellent and easily understood definition.
- V. The vastness of the numbers in this section are so difficult to fathom! Think of how you yourself have trouble grasping the times and populations. That is OK; enjoy the wonder, and encourage the students to do the same.
  Students who have had geology will find the presentation here to be scanty. Remind them this is a biological overview and not an in depth geological study!
- V.A. Why would researchers have found organic molecules in Greenland that have not been altered by heat or pressure? Also, is there an explanation other than microbial photosynthesis to account for the presence of chlorophyll breakdown products in Rhodesia?
- V.E.2. Stress Figure 17.19.