Bring the real world into the classroom.

Motivating students is easier when props, demonstrations and hand-outs are an everyday occurrence.

In my opinion professors teaching engineering subjects should have a big advantage over many of their teaching colleagues in other faculties. This is because most of what we teach has

In this article I will describe a teaching style that has been very useful for me. It involves using visual aids ("props"), demonstrations and hand-outs - what students sometimes call "show and tell". In fact that was the title I used for an earlier article on this method [1]. The focus will be on using aids in a heat transfer course but the ideas can easily be used in other courses as well. My former PhD student, Suzanne Kresta, MCIC recently published an excellent article describing several demonstrations that she developed which can be used in a fluid mechanics course [2]. Other courses such as mass transfer, thermodynamics, process control, reaction kinetics and the introductory chemical engineering course seem amenable to the methods described here. The idea is, insofar as it is possible, to bring the real world into the classroom.

Why Bother with "Show and Tell"?

Stice [3] lists the following 10 characteristics of good teachers: the good teacher: (i) knows the subject matter, is competent; (ii) presents well prepared lectures; (iii) relates the subject to life; (iv) encourages students' questions and opinions; (v) is enthusiastic about the subject; (vi) is approachable, friendly and available; (vii) is concerned for students progress; (viii) has a sense of humour; (ix) is warm, kind and sympathetic; and (x) uses teaching aids effectively. Some of these characteristics are part of one's personality and are difficult to change. However, a professor can improve his or her teaching (and teaching evaluations by students) by including several demonstrations or props in their classes as some of the above characteristics are inter-related. For example by choosing timely topics for demos that are relevant to the student, objectives (iii) and (x) are met. Preparing and integrating these into the class means that (ii) is satisfied and a good demo will lead to questions and discussion so (iv) is likely to happen as well. Finally, presenting demos and using props that students can relate to, demonstrate enthusiasm in the subject matter (v) and bring the professor to the level of the students hence even some of the personal characteristics are demonstrated. There are of course other models for what "good teaching" is but most suggest techniques such as the ones described here.

Another good reason for using "show and tell" relates to the students learning styles. In the recent past several papers have appeared describing and discussing learning styles and how a knowledge of them is of use to a teacher. In fact the Myers-Briggs Type Indicator of learning styles has become a widely used tool in everything form business groups to church groups. One of the leading proponents of using the knowledge of students learning styles to improve teaching in the engineering literature is Rich Felder [4] who frequently writes about it in the journal Chemical Engineering Education. In his article describing how to reach students who are normally not well served by the traditional lecture style, Felder proposes several modifications that one can make to his or her teaching style to reach this group. Among others, these include: (i) motivating theoretical material by first discussing the physical phenomena involved and what types of problems the theory will be used to solve, (ii) balancing concrete information with conceptual information in all courses, (iii) using sketches, plots, demonstrations and props in addition to written explanations and derivations, (iv) using physical analogies, rules of thumb or experience factors, and (v) providing time in class for students to think about the material being presented.

My experience is that the use of props and demonstrations in my classes reaches students at all levels and they frequently make positive comments on them in their teaching evaluations of me.

Examples of Props and Demonstrations

Hardly a day goes by when I don't use a prop, a demonstration or a hand out (or all of them) in one of my classes. Last week for example we discussed the wind chill effect. My students had heard about this concept of course (and given the weather we were hearing about it very day) but they didn't know that the concept was based on convective heat transfer - which they were studying at the time. They also found it interesting that the inventor of the concept was a graduate student, not much older than them. I have prepared a two page hand-out detailing the history and heat transfer of wind chill with hyperlinks to several web sites. Students learned of some of the pitfalls of the widely used formula and ways in which it might be improved. Most importantly it is tied to material they are learning so it makes their learning fun and relevant.

In my most recent class I used my smallest visual aid - a piece of copper shot (i.e. a "BB"). We had been discussing the notions of mathematical modelling and how it is applied to heat transfer for obtaining a differential equation describing the temperature by performing an energy balance. Of course, one of the key steps in performing the energy balance is to determine the control volume, or system, over which the balance is applied. If the entire volume of an object can be used as the system (so-called lumped analysis) the analysis is easier and an ordinary differential equation results. I tell the students "we want this!" The important parameter to test is the Biot (Bi) number. If Bi [less than] 0.1 lumped analysis can be used. The BB has a very small Bi. The message to the student is to check the Bi. For large thermal conductivity and small size (and hence a small Bi like the BB) lumped analysis can be used. We then go on to derive the equation for temperature.

By far my most memorable demonstration is the beer cooling experiment, Wood [5]. Here we estimate the overall heat transfer coefficient for a can of beer that is cooling by natural convection in an ice bath. By measuring the literal "mixing cup" temperature as a function of time we are able to estimate the thermal time constant for a can of beer (7 minutes) and have a lot of fun doing it. Usually I have to turn away upper year students who have heard that the experiment is being conducted and want to repeat it.

Over the years I have collected several props that I make considerable use of. Some of them are shown in the photograph. A steam pipe with a 1 inch layer of Ca-Si insulation, partially cut away, is used to demonstrate steady conduction in cylindrical systems and leads into a design problem on the optimum thickness of installed insulation. This problem is made as "real" as possible by using accurate values for the cost of steam and the installed cost of insulation. A solid rod with removable insulation is used to illustrate axial and radial conduction and a very small copper water pipe is used when discussing the interesting concept of critical insulation thickness. I have built a mock wall with studs and insulation bats and covered it with Plexiglas to demonstrate parallel resistances. I also have a miniature heat exchanger and a CANDU fuel bundle that are circulated around the class when I am discussing the design of shell and tube heat exchangers and internal heat generation. I also use a variety of balls and hockey pucks to show the students what the appropriate control volume is in a number of modelling problems. (One year I had used the hockey puck so frequently when discussing the notion of plug flow that the students gave me a trophy at our "Roast the Professors" night calling me the "plug flow pro". On top of the trophy was a hockey puck).

I keep my eyes open for props and topical examples that I can use in my classes. When my computer was being scrapped I kept the CPU and heat sink to show the students what fins look like and why heat transfer is an important limitation on CPU design. I try to base tutorial examples (and sometimes even final exam questions) on "real world" problems.

Conclusion

My experience with using real world examples, props and demonstrations in class is that they can be used to illustrate the simplifications that need to be made to make a problem tractable but also allow generalization. Students are more interested then in applying their math skills to higher level problems, work harder and surprise themselves with regards to the complexity of problems they are able to solve.

References

1. Wood, P.E., "Show and Tell' in Engineering', Teaching Forum, University of Guelph Teaching Support Services Newsletter, ISSN 0380-3589, May 1995.

2. Kresta, S.M., 'Hands-on Demonstrations: An Alternative to Full Scale Lab Experiments', J. Eng. Educ., 87:7-9, January 1998.

3. Stice, J.E., 'A First Step Toward Improved Teaching', Engineering Education, 66:395-398, February 1976.

4. Felder, R.M., 'Reaching the Second Tier - Learning and Teaching Styles in College Science Education', J. Coll. Sci. Teaching, 23:286-290, 1993.

5. Wood, P.E., A Successful Heat Transfer Tutorial, 48th Canadian Chemical Engineering Conference, London, Ontario, October 4-7, 1998.

Philip Wood, FCIC is the 1996 winner of the CIC's Union Carbide Award for Chemical Education. He is a 3M Teaching Fellow (1993) and is presently associate dean of engineering at McMaster University in Hamilton, ON.