Douglas A. Bernstein
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Published Talks

Tell and Show: In Praise of Classroom Demonstrations


Douglas A. Bernstein
University of Illinois, Urbana-Champaign

After years of watching undergraduates nod off during what I thought were well-organized and fascinating lectures on research methods in psychology, I had no choice but to become a psychic. Expanding on an idea suggested by Morris (1981), I now casually mention my psychic ability on the first day of each semester, claiming that it emerged in the aftermath of a car accident that had left me in a coma for several days. The students are invariably enthralled; they can tell this is going to be a really good course! After lamenting that there will be no time in the course to explore parapsychology, I offer to demonstrate my powers of psi by trying to predict the future or read someone's mind. A few simple but very impressive tricks--described in magic books, textbook instructor's manuals, and other sources--are more than enough to convince students that I am indeed capable of precognition and telepathy. Their astonishment is short-lived, because I immediately debunk the tricks (without revealing the methods of trickery) and assign as homework the task of explaining how I might have accomplished "psychic" feats. The next class session is inevitably a lively one in which students propose a number of explanatory hypotheses and suggest research designs capable of eliminating incorrect alternatives. Reading the assigned chapter on research design makes the students' task easier, and they seem a lot more interested in that chapter than their counterparts in my pre-psychic days.

Using "psychic" demonstrations to teach research design takes a bit longer than presenting a lecture on that topic; indeed, by their very nature, most classroom demonstrations take time away from lecturing. However, I think there are at least three reasons why this may not be such a bad idea.

First, because demonstrations are distinctive and offer a change of pace, they tend to attract students' attention. This is good, because there is evidence that most students remain focused on our lectures mainly during the first ten minutes of class (Stockin, 1994); at any given time after that, about 80% of them are worrying about something, having erotic thoughts, reminiscing, or thinking about lunch (Cameron, 19xx). The attention-getting value of demonstrations is especially high when all students can actively participate in them rather than passively observe them. So though you can demonstrate compliance with authority by asking one student to, say, whistle a tune, the others might not be as attentive as they would if you asked the entire class to hop on one foot or to give the instructor a standing ovation. (This particular demonstration has the added advantage of making it impossible for any student to claim immunity to social demand characteristics.)

Second, even if you never did a single demonstration in the classroom, chances are that you will never have enough class time to cover about everything that is in your lecture notes, let alone in the textbook. Ok, you could if you talked as fast as that guy on the old Federal Express commercials, but could your students process the information? Speaking of which, just because we find time to lecture on something does not guarantee that our students will encode, store, and be able to retrieve the material. Thus, even if demonstrations do not themselves teach more than lectures do (see McKeachie, 19xx and Muir & Webster, 1994, for data on the controversy over the relative value of demonstrations vs. lectures for teaching complex vs. simple material), they can certainly illustrate concepts found in the textbook and thus make it easier and more enjoyable to learn by reading the text. In fact, my 27 years of teaching have left me convinced that the best use of class time is not so much to teach things as to do things--tell stories, give examples, present new concepts, and of course offer demonstrations--in ways that motivate the students to read the book, ask important questions, and learn for themselves.

Third, classroom demonstrations, like other breaks from the straight lecture mode, can provide highlights that make teaching more enjoyable for you as well as the students. Having highlights to look forward to each day is important because teaching courses again and again can easily become boring. When teachers are bored, their students know it (Appleby, 19xx) and they become bored, too. And passive. And maybe even a little hostile, especially when filling out class evaluation forms. It is no wonder that some faculty come to feel that teaching is not much fun, or at least not as much fun as it used to be. Demonstrating course content in ways that generate student involvement, responsiveness, and enjoyment can help maintain your enthusiasm in the classroom year after year. I am not by any means arguing that faculty should stop lecturing. I am only suggesting that virtually any lecture can be enhanced by weaving into it demonstrations of varying length and complexity. At one end of the continuum are demonstrations--such as two-point threshold measurements--that require interrupting the lecture, distributing equipment, data sheets, instructions, and other materials, and 15-30 minutes of class time to complete. As already noted, I think exercises like these have a valuable place in the classroom now and then. At the other extreme are quick demonstrations that can be integrated into a lecture so smoothly as to hardly disrupt its flow. When lecturing on size constancy, for example, you can quickly and memorably illustrate Emmert's Law (Perceived Size = Retinal Image Size x Perceived Distance) by having the class look at a camera as you fire its flash unit. The resulting afterimage (whose size is fixed) will appear larger when the students look at a distant wall than when they hold their palms in front of their eyes. Similarly, it seems a shame to lecture about progressive relaxation training methods without having the students put down their pens, close their eyes, and listen for just a minute or two of (live or taped) relaxation instructions.

How do you decide whether, and where, to include more demonstrations in your courses? One way is to ask yourself whether there are lectures that you do not look forward to because they feel stale to you and/or don't seem to interest your students. If there are, there are probably demonstrations that could break up and enliven the presentation--for you as well as for your class. If you choose to add new demonstrations, do keep in mind two important guidelines that many experienced teachers have had to learn about the hard way.

First, it is rarely a good idea to try out a new demonstration for the first time in front of your class. Practice ahead of time on friends, family, colleagues, or even alone, just to be sure that you are clear on all the instructions and procedures, and above all, that the demonstration will actually work the way it is supposed to. The importance of rehearsal is well illustrated by the experience of a colleague who shall remain nameless except for his initials, Lou Penner. To demonstrate one of the practical applications of operant conditioning principles, Lou arranged for a local police officer to put a police dog through its paces on the stage of Lou's large classroom. The officer and dog were stationed at one side of the stage and a student volunteer, wearing a protective cuff, stood at the other. At the "attack" command, the animal sprinted for the student and, at the "halt" command, immediately attempted to stop. A rehearsal would have revealed that the stopping distance for a large dog hurtling across a highly polished wood stage is a lot longer than one might think. Contrary to plan, the dog actually reached the student, who was a bit shaken (though unhurt) by the experience. Not all demonstrations can go so dramatically wrong, but a dry run can reduce the chances of losing class time and confusing your students.

Second, it is vital that every demonstration is clearly linked in the students' minds to the principles or concepts it is designed to illustrate. This is an especially important concern when a demonstration is so funny, game-like, or absorbing as to stand alone as a pleasant diversion from the "regular" course material. Consider the rumor chain, for example, in which a story is passed from one student to another until its content is markedly altered. This exercise can nicely illustrate phenomena such as leveling and sharpening, distinctiveness, constructive memory, the influence of gender and ethnic stereotypes on recall. However, if the students are not prepared to listen for and take note of changes in the story, and if afterward there is no opportunity for them to identify the principles illustrated by those changes, the time spent on the demonstration, though enjoyable, may have been wasted.

Still, I think the potential benefits of classroom demonstrations far outweigh their perils. As a means of holding students' attention, motivating them to read and ask questions, and making teaching more enjoyable for the teacher, demonstrations are hard to beat. And new ones are so easy to find. Information about effective demonstrations on virtually any topic in psychology is readily available from the instructor's manuals that accompany most textbooks, from specialized handbooks (e.g. Benjamin, Daniel, & Brewer, 1985; Makosky, et al., 1990) from journals such as Teaching of Psychology, and via electronic mail networks such as TIPS (Teachers Interested In Psychological Science; subscribe by sending the message: subscribe tips Yourfirstname Yourlastname to LISTSERV@FRE.FSU.UMD.EDU on Internet or to LISTSERV%FRE.FSU.UMD.EDU@CUNYVM.CUNY.EDU on Bitnet).

Give some of these sources a try. I suspect that you will like the results of enlarging your reportoire of demonstrations, and that your students will, too.


References
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