Lewis/Life - Teaching Techniques

Chapter 32 - Teaching Techniques

A. General Tips
** See the General Tips notes in Chapter 30 of this Instructor's Manual.
This is a fun chapter. Students generally like learning about the senses. After all, they are all very familiar with how things look and taste and smell and sound and feel!
Your major goal should be to instill in the students an awareness of sensory perception. Concentrate on the anecdotes and use the Mastering Concepts questions for anatomical background. Read this chapter carefully yourself; you will find many points that will truly interest your students and will help them acquire a clear conceptual understanding of sensory perception.
You will find your students have a few misconceptions connected with this chapter but mostly you will find they have a keen sense of curiosity.
Bring in models of the eye and ear so you can demonstrate the parts directly.
Throughout this chapter you will find numerous opportunities for extra or outside assignments. These can be good assignments for demonstrating the principles of scientific methodology as well as for involving the students in every day practical scientific problems.
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
** Here are some quick non-quiz questions. The answers are all true. 1) A very old dog who is almost blind and deaf usually still has a very keen sense of smell. 2) Natural gas is odorless so gas companies add an odor so we are immediately aware of a gas leak. 3) Reading continually in poor light will not cause visual damage, though it may make you frustrated or give you a temporary headache.
** Here are three quick sensory experiments you can use to begin your discussion of this chapter.
- 1. Pull a brown paper bag from your brief case, set it on the lecture table and begin the class by dramatically announcing that you have just brought in some very fragrant cologne. Ask if the students can smell it. Watch the reactions. Some students will tilt their heads and narrow their nostrils. (Narrowing the nostrils to sniff concentrates the smell and heightens awareness.) Some students may close their eyes. This reflex blocks out the visual sense and allows for greater concentration on the olfactory sense. After everyone's anticipation has been piqued, explain what happened.
- 2. Ask your students to jot down what their shoes or socks feel like right at that moment. Again, watch the reactions. Some will look at their feet. They are adding another sense in an attempt to get a more accurate description. Some will begin moving their feet. This will heighten the sense of touch. Explain that they were basically unaware of the touch sensations from their feet until they deliberately thought about them. They were able to selectively process information.
- 3. Ask everyone to take one finger and very quickly point to some object in the front of the room keeping both eyes open. Now, holding their arm still, they should close one eye and then the other. Ask which eye was open when the finger was on the object. That eye is the dominant eye (and has nothing to do with whether the person is right or left handed). The focal points between the eyes should be separated by about 3°.
C. Hints Related to Specific Chapter Topics
- I. As a point of interest, note that bats can see and many of them see quite well. They simply use echolocation instead of vision when echolocation is more opportune. "Blind as a bat" is inappropriate.
- II. & III. Good explanations and good anecdotes can be found in these sections.
- III.B. Sensory adaptation is sometimes called sensory fatigue and is sometimes broken down into its auditory, gustatory, visual, and olfactory components. Ask the class to jot down some real life examples. Why does the car radio seem so loud when you get in in the morning when it seemed perfectly fine when you shut the car off the night before? Why do visitors to your town comment on the smell from the local meat packing plant when you really have to concentrate to even figure out what they are talking about? Etc.
- IV.A.2. Students always like the visual explanations. Ask them to imagine the compound eye. What evolutionary advantages might there be for the arthropod?
- IV.B. Because of previous misinformation, many students believe that animals do not see color. Most of the vertebrates (including the family dog) do indeed see color.
  There are many possibilities in this section for extra or outside assignments.
- V.B.1. This section contains a great deal of very interesting information. Be certain you are comfortable with the material because the students will probably have a number of questions.
  Note that there are several different types of color blindness, depending on which cones are absent. Some people also suffer from a reduced number of certain cones. These people do not always perceive color unless they specifically concentrate on the color of the object in question.
- V.B.2. Bring in some lenses, either from your department or from the physics department, in order to demonstrate how lenses refocus light.