Lewis/Life - Teaching Techniques

Chapter 31 - Teaching Techniques

A. General Tips
** See the General Tips notes in Chapter 30 of this Instructor's Manual.
Your biggest concern will be what you will expect of your students. Refer to your course objectives. This can be a great chapter, but it can also cause a great deal of confusion for some of your students. You may even be surprised that some of your best students have trouble with action potentials.
Some instructors do not understand nervous system physiology very well themselves and think they can gloss over it by assigning it for completion outside of class time. This usually does not work too well.
Other instructors find nervous system physiology extremely easy and therefore assume their students will also find it easy. This usually does not work very well either.
Know what you are talking about and keep the physiology in perspective.
Numerous nervous system disorders are mentioned in this chapter. You might wish to assign some of these for regular or extra credit research. These disorders are fascinating to most students; they are also the source of a great deal of misinformation.
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
Use charts liberally. Construct these charts on the board or overhead as you go along.
Bring a brain model to class, particularly if your course does not have a corresponding lab. Use the model to demonstrate where the parts of the brain are located. Pass the brain around so students can see and feel it -- even if it is only plastic.
Do the nervous transmission "time" experiment listed below. Students will really be able to put a few ideas together.
C. Hints Related to Specific Chapter Topics
- III.A. Either teach this section or don't teach it. The ideas can be somewhat confusing to students who have never had this material before so it is not a good idea to simply skim over it.
  Note the electrical potential is given as -65 mV. This is an average number. There are variations in different parts of the body. Note too that some books use slightly different numbers but that the principle is the same.
  Use props to demonstrate the voltage gates. These props can be as simple as using your hands to simulate a gate.
  Ask the students to recall what an ion is. Some will have forgotten.
- III.B. Here is an experiment that is guaranteed to impress the time element of nervous transmission on your students.
  Have a watch with a second hand ready. Ask your students to stand and form a continuum around the room. (If you have a large class, you may need to have two or three such continuums.) Each student is to put his or her right hand on the shoulder of the next student. Designate the "start" student. You call time and that "start" student squeezes the shoulder of the next person. As each student feels the squeeze, that students squeezes the next student's shoulder to the last person. Record the time. You have just demonstrated the time element in electrical transmission.
  - Variation # 1: Right-handed students put their right hand on the right shoulder of right-handed students and on the left shoulder of left-handed students. Left-handed students use their left hand. Do the squeeze and record the time. Now do the opposite. Left handed people use their right hands and right shoulders; right-handed people use their left hands and left shoulders. Do the squeeze and record the time. (It should take longer with everyone using the opposite hand and shoulder.)
  - Variation # 2: Try it with both hands.
  - Variation # 3: Try it with both hands on the shoulders of the next person but use only one hand to squeeze. If the squeeze comes in on the right shoulder, squeeze the next person with the left hand. (Class laughter may necessitate restarting this one!)
  Analyze the variations in time. Make a list of conclusions. Ask if you have done a proper scientific experiment.
- IV. & IV.A. The class might be interested in the diseases of tetanus and botulism. Tetanus is caused when the neurotransmitter is not destroyed and thus remains attached to the muscle. The muscle remains contracted. Botulism occurs when the neurotransmitter is not released. Therefore, it cannot attach to the postsynaptic membrane and no contraction can occur. Flaccid paralysis results.
- V. Refer to your phyla charts from Chapter 26.
- V.A. The poriferan nerve response is not well understood. It is somewhat misleading to call the cnidarian nerve net a "net" because the nerve fibers do not touch. If they did, a short circuit would result, the same as it would if our neurons touched.
- V.B.1. You can demonstrate the formation of the neural tube very easily with a piece of paper. Before class take a piece of paper and tape the long sides together so that you have a simple cylinder. Take that to class. Hold one end of the cylinder in each hand. With your index fingers, push in an indentation the length of the cylinder. Hold it together. Now it looks like you have a tube within a tube. You have also demonstrated how the ectoderm folds around itself.
  Spina bifida can occur anywhere along the spinal cord. A very tiny opening might go unnoticed for life. Such an opening would cause no problems. Spina bifida usually does not affect intelligence.
- V.B.2. Figures 31.13 and 31.14 are highly useful. Use them generously.
  The statement is made that the autonomic nervous system is well developed in reptiles, birds, and mammals but less so in fishes and amphibians. Ask why this might be so.
- VI. The reflex arc is independent of the brain. In the spinal cord another synapse occurs; this takes the message to the brain. You can demonstrate this with two pieces of paper held at right angles. The one paper represents the transverse reflex arc. The other paper represents the information heading toward the brain.
- VI.B. The brain is the most selfish organ in the body. It will take its oxygen and glucose first. Why is this necessarily a good idea?
  The brain is the only organ that needs itself to study itself.
  Make a chart of the parts of the brain and their derivatives.
- VIII. Check the psychology of memory. Make note of what we do not know!
- IX.B. Students are often confused when they hear "fight or flight." These terms are essentially synonymous. Students often think they are opposites. The opposite of "fight or flight" is "rest or repose."
- X.B. Challenge the students to check into the new research on the possible regeneration of neural tissue.