THE SECRET OF GOOD OVERHEADS

Here's a trick that demonstrates something very interesting about the way the human brain works. You can use it to amaze your friends and co-workers at the next office party, but you can also use it to demonstrate why many overhead transparencies used in meetings, training sessions and presentations are so incredibly dull, boring, ineffective and just plain bad. (Plus, of course, you'll be able to make sure that your own overheads are all effective from now on. Really.)

Make an outline drawing of the capital letter E like the one below. Show it briefly to the subject of your experiment and then hide it from view. Ask your subject how many straight lines one would have to draw to reproduce it. Watch closely as he or she gazes off into the distance for a few seconds before arriving at the answer. (Twelve.) Then ask the same person how many Canadian cities have NHL teams, (or, if you travel in higher circles, how many Canadian cities have symphony orchestras). Watch again. This time your subject will gaze off into the distance, start naming cities and, almost invariably, count them up his or her fingers!

Why do we count the cities on our fingers but not have to do the same with the sides of a geometric figure? Because counting sides of the figure E uses two different parts of the brain, the part that visualizes a figure and the part that counts the sides; naming cities is also two operations -- thinking of them and counting them -- but those two tasks both use the same part of the brain. So, to keep track, we need our fingers.

Now think back to training sessions you've attended. What do you see? All too often, it's a person standing beside an overhead projection of a page full of point-form text. Talking. Now, unfortunately for the presenter, you have to choose between reading what's on the overhead or listening to what he or she is saying. You can't do both -- those two tasks use the same part of the brain. So most of us read half the overhead, listen to half of what the presenter is saying and never quite get the whole picture.

To get the whole picture, we need, well, a picture. Overheads are a visual medium; if you're going to use them, you have to use them to do what a visual medium is designed to do: present visual information. And if a verbal presentation is backed up by effective visuals, some truly magical things start to happen.

First of all, we can look at a picture and listen to the presenter talking about it with no internal conflict. The visual image and the verbal description complement one another. We don't have to choose between looking and listening, because we can do both at the same time.

Second, a picture is often worth a thousand words. There are some things that are just much better shown than explained. If you are describing the essential elements of proper scaffolding, for example, a diagram with a small amount of explanation is by far the easiest way to convey the information.

Third, the information in the picture-narrative package is presented to us in two different ways simultaneously. Some people will gain their understanding primarily from the picture with the instructor's explanation serving to set the scene and fill in the details. Others in the group, whose minds work differently, will gain their understanding mainly from the description, with the picture pulling it all together. Both will end up with a better overall understanding. Both will store memories of the picture and the explanation in different parts of the brain. (And remember it twice as well.)

Finally, the interplay between the picture and the explanation in our minds serves to light the spark of sudden understanding -- Aha! Now I see it! -- that is the heart and soul of all learning.

How to do it

Many course developers seem to believe that the words "training" and "overhead" are synonymous; they're not. Many developers believe that you need at least one overhead for every objective or sub-objective in a presentation; you don't. And many believe that providing a complete set of overheads "covering" every point in a packaged presentation will ensure that the instructor doesn't get lost or stray from the canned package; perhaps it does, but at what cost? (When mandatory training was introduced for "certified" members of Ontario health and safety committees several years ago, the course consisted of over 750 overheads -- most of them filled with point-form text. However, the course was radically shortened and opened up to other training methods a year ago, presumably in time to forestall the flood of repetitive strain injuries that might have resulted if course instructors had had to continue flipping overheads at that rate.)

A good instructor delivering a well-designed course relies on a variety of methods and media, always using the best technique available to make each point and achieve each training objective. Sometimes that means lecture, Socratic questioning, discussion or exercises; sometimes it means using a blackboard or flip chart; and sometimes -- when there is a visual element that needs to be shown -- it means using overheads.

What sort of information is best conveyed using overheads? There are basically two kinds: First, many things are easier to discuss if the group is looking at a picture, map or diagram; second, some concepts are easier to understand if they are represented by a chart, graph or diagram. Some examples are listed below.

* Labeled diagrams: If you have to explain the parts of a fall-arrest system, there's nothing quite like a large picture on the screen to make the job easy.

* Flow charts: A flow chart is a visual representation of a process. It can help people to "see" it conceptually and to grasp the order and relationship of events. It can represent movement of material, changes over time or causes and effects. As long as there are not too many boxes, arrows and feedback loops, they make wonderful overhead material.

* Graphs: Occasionally -- very occasionally -- a graph may make a good visual for an overhead. As long as the are kept simple, and as long as they illustrate some key point that you need to make, they can be quite effective. A five-year comparison bar graph showing accident frequency or cost, for example, can give your group the whole picture at a glance. But be aware that nothing gets boring more quickly than a series of graphs, especially if they are complicated, if they mix apples and oranges or if there are too many footnotes.

* Organization charts: The familiar "org chart", with the board of directors in a big box at the top, the president in another just below it and arrows leading down to parallel columns headed by vice-presidents, is the classic example. It can be used to describe the structure of any sort of organization -- not just management hierarchy -- and it shows the relationships, status and positions of all the elements.

* Photographs: While overheads don't do the best job of showing detailed photos, they can often be quite adequate. (Of course, if you have a lot of pictures, a slide projector or high-end video display would be the route to go.)

* Cartoons: A cartoon -- a funny and often irreverent picture of a scene from life -- can capture feelings, express attitudes or sum up the essence of a situation.

* Word charts: Sometimes you can use words on an overhead to represent elements in a diagram. (This is useful when the elements don't lend themselves to symbols or pictorial representation.) The number of words has to be kept to a minimum so that they can be grasped at a glance without taking time to read.

If you absolutely have to put text on an overhead -- a series of points you need to discuss with the group, for example -- there are two generally accepted rules to keep in mind. First, make sure the type is big enough for everyone in the back row to read. That depends somewhat on the size of the room, but a rule of thumb is to make the text on the acetate at least one-half inch high. The second rule is that you have to limit the overall amount of text to "6 X 6" -- no more than six words in any line, and no more than six lines on any overhead.

Finally, we do have to admit that there are times when blocks of text are acceptable on an overhead. Since the argument against text on overheads is that it prevents people from listening to a presenter, it follows that text should be okay if no one is talking. So some text blocks are fine: A scenario for group discussion, the questions for a review quiz, and instructions for some activity to be performed by the group are all examples. Using an overhead in this way saves paper, reduces the need for off-site photocopying and makes the presenter's burden of materials a little lighter.

Okay, here's another trick that will amaze your audience. Show them a dozen really good overheads that help them visualize key elements of your presentation. Watch their eyes very carefully. Notice how they're still open and not glazed over?

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