Lewis/Life - Teaching Techniques

Chapter 24 - Teaching Techniques

A. General Tips
Studying the fungi can be an exciting adventure for both you and your students. Many outside reports can be generated from the material included here. This is also a chapter that lends itself well to anecdotes.
Use the pictures in this chapter. Also, ask students to share some of their own adventures with fungi. For instance, if you call attention to Figure 24.2, you will find that many of your students have seen bracket fungi when hiking in shaded, wooded areas.
Probably one of the most interesting understatements in this chapter can be found on page 480: "Despite the fungi's widespread distribution, we know very little about their diversity." Use this observation to help add excitement to the fungi.
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
I suggest beginning this class by asking the students to write down about 10 uses of fungi. Most will not be able to do so. You might also ask them what that black stuff is that grows in the caulking in the shower. And when they tell you mold or mildew, ask them what the mold or mildew uses as a food source. Watch the reaction when they figure out the nutrient value of their sloughed skin. And the shower provides such a nice warm, moist environment for the little fungi!
Use this class to introduce your students to a world most of them have never before considered.
If you did the in-class bacteria experiment suggested in the monera chapter, and if you saved the agar plates, you probably still have some good fungal samples.
Ask your students to check their refrigerators (or check your own refrigerator!) for some additional fungal samples. Put the samples in petri plates and keep the petri plates taped shut. Bring a magnifying glass to class. Pass around the fungal samples and the magnifying glass. If anyone brought in some black bread mold, everyone should be able to see the various fungal parts quite easily.
If you have access to a bioscope or some other projecting microscope, give a class demonstration of some of the fungal samples. Also, use the projecting scope to pull apart the gills of a fresh mushroom. You do not have to be a great mycologist to excite the students with the fungal world. Most of them have never given much thought to fungi, except to think, "Yuk!"
Another neat lecture hall demonstration is growing yeast. Either try this beforehand because the timing depends on the temperature of the room as well as the age and condition of the yeast or set this up at the beginning of class and put it immediately under the projecting microscope. Leave the scope on as you begin class and when the action seems to be beginning, stop lecture and concentrate on the yeast. Any grocery store yeast will do. Put equal amounts of ordinary sugar and yeast in a glass of warm water. Add a dash of salt. Measurements do not have to be exact! After about 20 minutes (give or take) take a sample and put it on your projecting scope. The students will be able to see the yeast cells swarming and probably dividing. Add a drop of methylene blue.
C. Hints Related to Specific Chapter Topics
- II. A number of the "myco-" words are listed in this section. Explain that any time "myco-" appears, the word probably has to do with fungi. Include mention of products such as Mycotin®.
- II.A. As stated, the primary storage carbohydrate for the mushroom is glycogen. You may have to re-identify glycogen.
- II.B. Some points of interest: Fungal dimorphism is often related to the environment, particularly the temperature. Strands of yeast buds are often called pseudohyphae. When yeast bud, the parent cell exhibits a "birth scar" and it is possible to tell how many times a yeast cell has reproduced by counting its "birth scars." The pores found in the septae of septate hyphae come in species specific sizes and shapes.
- II.C. Some books will tell you that lichens are more properly called lichenized fungi.
  Note the paragraph on page 479 beginning, "When fungi reproduce...." I suggest you have a good grasp of this paragraph because often a student will ask a rather complicated question.
  Should you decide to expand on fungal reproductive strategies, check the diagram I have included with Chapter 28 of this Instructor's Manual. That diagram can be used for any sexually reproducing organism.
- II.C.1. Sketch out this mimicry. That will help the students understand what is really happening. You might also invite outside investigation of other fungal reproductive strategies.
- III. Note that fungi are ubiquitous! They are found even on mountain peaks and at ocean depths.
  Note the word Cryptoendolithic. Show the students how this word means exactly what it sounds like it means.
  If you have the time, ask the students to figure out how scientists know how a single individual Armillaria luteobubalina organism covers 37 acres.
- IV.A. Stress the adaptive value of sexual reproduction. Ask the class how this is so.
- IV.B. The statement given is that many of the bluish green fungi are ascomycetes. This is certainly true. Many of these growths are actually Penicilliums. Be aware that on page 483 is the statement that some mycologists do not accept the Penicilliums as ascomycetes. For your purposes, this is just semantics.
  Pigs love truffles. The classic way of finding this subterranean delicacy is to let a pig loose and note the trees where the pig starts to dig. Those trees will have truffles at the roots. Today dogs can also be used to sniff out truffles. This is often easier than arguing with a pig!
  You might ask your class why morels are not mushrooms, even though they are sold as mushrooms in the grocery store. Mushrooms are basidiomycetes; morels are ascomycetes.
- IV.C. Puffballs are delicacies, but be careful. See the notes below under V.C.1.
- IV.D. The points about the deuteromycetes are excellent examples of the flux in the emerging science of taxonomy.
- IV.E. Some points on lichens: These organisms are truly an example of the whole being more than the sum of its parts because the whole behaves differently than the individual parts. Lichens come in all colors. Lichens also come in several distinct shapes. "Reindeer moss", the small grubby plant of the Arctic, is really lichen. The algae and the fungi each reproduce independent of the other. Lichens are used to obtain litmus and present research is indicating that lichens could be a possible source of antibiotics.
- V.A. Most students will be surprised to learn that the fungi probably diverged from animals (rather than from plants).
- V.C. Emphasize that plants get diseases too. You may have to remind a few students what a sterol is.
- V.C.1. Tinea (from the Latin for worm) is a word often used for ringworm. Tinea can technically be used for any mycosal skin disease. The Tineas are the diseases which include athlete's foot (Tinea pedes), "jock itch" (Tinea cruris), and ringworm of the scalp (Tinea capitis).
  The mycoses are generally less severe, but longer lasting and more of a nuisance, than are bacterial diseases.
  Mention is made of the puffballs. Some people like to slice, toast, and butter puffballs. This is fine but people should be cautioned to know what true puffballs are and to be careful when doing this in the spring.