I was on data-projector duty at church yesterday. That meant I had to press the buttons that made sure the correct verse of the song was showing at the correct time, a job that requires more concentration and co-ordination than you might think. When I’m sitting close to a projector, I find the way that dust particles light up and darken again as they drift through the beam quite hypnotic. It reminded me yesterday of the occasions many years ago (I guess it would have been about 30!) when Dad used to set up his slide projector in the lounge and we’d look excitedly at his pictures from our last summer holiday. What technology!
But something about the slide projector really confused me, for a fair while. (And I don’t think I ever asked Dad about this.) And the blame lies squarely at the feet of Roald Dahl. Yes, Roald Dahl, as in Charlie and the Chocolate Factory, the BFG, James and the Giant Peach, etc.
You see, in Charlie and the Chocolate Factory, before Mike Teevee has his unfortunate encounter with Wonkavision, Willy Wonka explains how TV works – the subject gets broken down into lots of little pieces, and then beamed across the the screen, where they get reassembled again.
Now, that isn’t all that unreasonable for a description of television in a children’s book, but, for me, it meant that I confused those bits of dust caught in the projector beam for the bits of the image being beamed over to the screen. What was really perplexing was how, when I watched those bits of the image, they moved so slowly and randomly (some even moved towards the projector, not away from it) but the image appeared instantaneously when the slide was switched. I knew I couldn’t have my understanding right, but for a little while I couldn’t put my finger on what was wrong.
I could say that the moral of this is not to extract too much understanding from children’s books (the dangers of too much chocolate and coveting squirrels notwithstanding) but really it’s about misconception. It is so easy to pick up an idea about how something works or behaves, and, if it is the wrong idea, it can cause real problems for your understanding of further concepts. It will probably confuse you no end, but you may not know why. Part of the role of a science teacher (i.e. me) is to spot those misconceptions and correct them. That is not always an easy task.
I’ll end by saying that one of my pet hates is when physics ideas are portrayed incorrectly by the media etc. (How many times do you hear people talk about powers of 400 kilovolts flowing through a line?) There is, unfortunately, a real physics howler in Jostein Gaarder’s otherwise wonderful book on philosophy, Sophie’s World, where the explanation of why the moon remains in orbit around the earth is just appalling. It almost ruins the book for me.