A new concept is often best explained by means of an example or an analogy. It is not easy to come up with a good metaphor every time: Some educators and instructors are more adept at it, some less so. That said, we can list what to avoid while giving a learner an analogy to explain a concept. Here are three mistakes educators make in formal as well as informal settings. 

Assuming that the learner has specialised knowledge. I recall, in a physics class, a professor giving an example of how AM (amplitude modulation) in radio waves relates to FM (frequency modulation). The class had already been introduced to AM, and the professor asked us to think about FM vis-à-vis AM in terms of a more advanced concept. “Think of AM as space: You can see the change in the radio wave. It goes more up and more down. With FM, it’s like time: You can’t see it. It’s how often the wave goes up and down.”

That explanation might be valid, but for many students, it was difficult or impossible to relate to. A much easier analogy would be: “Using AM is like constantly changing the loudness of your voice. With FM, you keep changing the pitch.” 

The point here is that the former analogy might actually be good. It might give some learners a deeper insight about the topic than the second example can. The problem is, the first one assumes that the learner has an idea about space and time — an assumption that is probably not valid. It’s best to get to the lowest common denominator.

Being factually correct is more important than it might seem. When an instructor or guide introduces a fresh topic, analogy is a powerful means to map one’s way along the learning path — but analogy has an equally powerful potential to mislead. Start someone off with an incorrect metaphor, and he/she will struggle for the rest of the topic. 

As an example, I’ve seen a e-book that introduces the Meridian System of Traditional Chinese Medicine (TCM) thus: “Think about the meridians as highways along the body, with the organs as towns. So the ‘kidney meridian’ is like a highway that passes through one major ‘town’ — the kidney.”

As it happens, this can be a rough introduction to the Meridian System — but only in informal conversation. To the student of TCM, however, the metaphor will stick; as it happens, it is incorrect. Being vague but factual is better, as at EclecticEnergies.com: “Liver [meridian] is partly the liver but also something throughout the body, ‘Lungs’ [meridian] is not only lungs but also skin.”

Avoid humour. A joke, or humorous analogy, can steer attention away from the topic and dilute its essence. Worse, a casual analogy can get the intended message across to a learner while also imprinting an incorrect idea. 

You could start off introducing William Blake to a poetry and literature class thus: “Blake was to Whitman as a 70s Volkswagen Beetle is to a Ford Pickup.” The analogy has something to it, and it might even be insightful. But as far as the student of poetry is concerned, the two poets — Blake and Whitman — will have been distastefully (and one-dimensionally) labelled. It can be hard to overcome the metaphor.

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