I was pleased to discover that I am not the only chemistry teacher to make use of the fact that molecules sometimes have the appearance of more familiar objects. Evguenii Kozliak points out that the structural formula of citrate ion can be drawn in such a way as to resemble a flying bird (1). The author extends that image to help students remember the steps of the tricarboxylic acid cycle.

Dog with ball

In one of my general chemistry lectures many years ago I held a ball-and-stick model of acetic acid in front of the class. A student remarked that the model looked like a dog holding a ball in its front paws. Indeed, it did. I went on to explain that acetic acid is a weak acid and that its proton dissociates reversibly. And I concluded by showing the dog losing its nose and scampering around to retrieve it. Since students are more familiar with dogs than with weak acids, my point was made. This little trick has been part of my teaching repertory ever since.

I submit that visual analogies such as these can help the learning process. While we should not overuse them, they do build student confidence for the work ahead. Perhaps we can all remember a time when a little trick helped us in our studies.

Literature Cited

1. Kozliak, E. I. J. Chem. Educ. 1999, 76, 1656.