Pop. Sci book or Textbook?

I recently read a “popular science” book on a topic that I felt I needed to learn more about. The book was well-written, ideas were clearly explained, and I finished the book knowing a lot more about the history of the subject. However, I’m not sure I understand the key ideas in the book any better. I won’t mention the name of the book or the author because this post isn’t really about the specific book – it’s about how I suspect books of this nature often fail to deliver on what they implicitly promise: that you will understand the science contained within their pages. I’m not alone in this – someone recently told me that they had read two of this year’s most successful popular physics books, but felt they hadn’t really understood much of either.

There’s a belief that seems to be held by many science communicators and science teachers that if you can simply come up with a clear enough explanation for something in science, then your audience or students will understand it. I don’t think this is always, or perhaps even often, true. (On a related note, I don’t think that the frequently quoted notion that “if you can’t explain something to a six-year-old / your gardener / granny, you haven’t understood it” is true either, but I’ll save that discussion for another time).

Listening to, or reading, a clear explanation of a scientific concept or model can be the first step towards grasping it. However, in my experience, real understanding usually takes repeated engagement with the ideas, and actively trying to apply the explanation to situations or phenomena that are different to the ones originally provided. As my friend Ben Craven puts it, a key test for “understanding” of a scientific idea or model is that “your knowledge of it is such that you can do things with that knowledge in circumstances other than those in which you first understood it”.

Here’s an example: All year 7 students (11-12 year-olds) are supposed to learn about the particle theory of matter – the idea that everything is made of particles (atoms or molecules) and that the more energy these particles have, the more they move about. This, they are told, explains the differences between solids, liquids and gases, and they might be shown a diagram like the one below from BBC Bitesize:

It’s a deceptively simple sounding idea, and one which students cover at least once again before they finish their compulsory science education at the age of sixteen. Yet every year, I encounter new A-level students, (16-17 year-olds) who are incapable of applying this model when answering questions in class or in tests. And this suggests to me that they haven’t really understood it.

It is only through asking our students questions, first in classroom discussions and later in tests, that we give students the opportunity to try out their understanding – and it is only through observing them do this that we, as teachers, can make any judgements about the extent to which they have, or have not, understood whatever it is we’ve been trying to teach them. It’s this key step towards understanding that is (understandably) missing from most, if not all, popular science books. Which is why it might sometimes be better to buy a textbook, and work your way through the questions, than to read the latest tome promising enlightenment in six easy to read chapters.


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