THE TEACHING ECONOMIST - William A. McEachern 
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Issue 2, Spring 1991
William A. McEachern, Editor
Chalk Talk
Instructors who have given little thought to their use of the blackboard tend to make poor use of that teaching tool. Some instructors erase a little patch of board at a time -- just enough to squeeze in another topic. When class is over, the board is a crazy quilt of ideas. Someone just coming into the classroom would make little sense of it. Using the board effectively is physically and mentally demanding, but students get more from the combination of media than from a verbal presentation only.
Think of the blackboard as a large piece of writing paper. If you scribble all over the paper in no apparent order, anybody trying to uncover the connections among ideas will have difficulty following your reasoning. But if you use the board in an ordered way to present material in a logical sequence, students can see where you have been and where you are going. A logical ordering is important because some students are always trailing your presentation; they are one or two points behind and they need the written cues the blackboard provides.
Students usually write down whatever is written on the board. Since you don't have time to write everything you say on it, put only the central points on the board. First present the point verbally. Second, write the point on the board, saying each word as you write it. Finally, step back and read what you have written. This procedure helps students take good notes.
The blackboard is an especially effective medium for presenting graphs because students are able to see, in a step-by-step manner, how the graph was constructed and how curves shift. Before presenting the graph, take time to provide the economic intuition of what you are about to present. Many textbooks and instructors use graphs the way a drunk uses the lamp post: more for support than for illumination.
Some instructors rely on transparencies as an easy way to present graphs. But a transparency typically presents a finished picture. Students don't get to see how the graph is constructed or how a curve shifts in response to some change. Because students are busy copying that picture, they are distracted from your explanation of it. A new development in transparencies now offers the ability to present a complex graph in a step-by step manner through a series of attached overlays. Beginning with the simple skeleton, the graph can be built up as additional overlays are flipped over. This provides instructors with an opportunity to explain each step. Incidentally, the support package accompanying my textbook (Economics: A Contemporary Introduction, 2nd Ed., South-Western College Publishing, 1991) offers these Innovative Teaching Transparencies.