Monday 13 April 2009

Insulation from Physics

Stellar is having her time wasted by CGP Physics from the looks of things. Here is a GCSE Physics question she has to answer:

"Tom decides to insulate the loft. This costs him £350, but reduces the amount he spends on wasted heat to £255 per year. Calculate the payback time for fitting loft insulation in Tom's house."

If Stellar will forgive me for a comment like this, that is about as appropriate for her age as it was of my History teacher, when my class were 15 and 16, to show us a cute Walt Disney version of "Animal Farm" and spend the next several lessons with a worksheet to "put all the events in order". Instead of the terrifying message and the analysis of the tyranny, divisiveness and dishonesty, we got sparkly-eyed bouncing farm animals.

Is that GCSE question physics? Isn't it economics, building, arithmetic and environmental science? All of which are important. And all of which have a tenuous link to physics. And all of which is frankly just boring grown-up stuff on a par with the stock market and income tax. Physics is widely criticised as being boring and inaccessible. The least we can do, therefore, is to keep it about what it's supposed to be: how our incredible Universe works.

Paul Lockhart wrote about how miserable it is to "make math relevant to everyday lives . . . people enjoy fantasy". Same with physics. Physics is deep thought. At least let's keep some of the mystery and excitement of the world going before we start worrying about wall cavities and loft insulation. There will be adult years enough to stress about that.

If there are some physics principles to teach about insulation (after all, everyone should know about conduction, convection and radiation - how can I get this bottle to the other end of the classroom? I could throw it, carry it, or pass it along), at least make them intriguing. What about fat versus fur, the way different members of the animal kingdom insulate themselves? What about how to insulate an astronaut in a space suit - keep the dangerous radiation out, and keep their heat in?

I concede that there are many important and useful topics that don't quite fit into any lesson, environmentally friendly building being one of them. (It was a running joke when I was at school that the exam boards changed their minds every year about whether plate tectonics was chemistry, geography or physics.) This is where things like citizenship and general studies come in. Because, nearly two years ago - just when I was about to start teaching - I read a very serious off-putter by Wellington Grey.

Much of what he says turns out to be just too right. I disagree on one point - about the calculations. He was probably teaching a different course, but I watched many difficult and essentially unfulfilling calculations taking place in GCSE Physics lessons. They didn't make inherent sense to me, because - just like with Lockhart's experiences in maths - students were given a formula and told to apply it, rather than encouraged to prod the world and derive it for themselves. Rather than make students learn "F = MA", what about having, "OK, now what if one of you gets very cross and throws their pencil case at somebody's face. You want maximum impact before you get sent to the Head and expelled, so you might just as well make it worth it. What should you do?" Students would advise throwing something heavy and fast. And then: Why? Why why why? Does one have more effect than another? (Before the let's-point-out-the-obvious troops descend, I am not advocating that such behaviour be encouraged!)

For a real example, the head of science at one school I worked in was sighing one day about the experiment to measure the Earth's gravity using a pendulum. You set up the equipment, you get them to use such precision - "and then you give them a formula which they don't understand", i.e. G. Conjuring rabbits out of hats isn't science either. OK, I'm off on a tangent now. I wonder if the syllabus even includes why air is a poor heat conductor?

I particularly agree with him on one point - the pointless debating. I'm not sure that precision attracts many pupils - actually, it's a very frightening prospect for most, though probably magical for a few. It is particularly pointless to get kids to have an opinion on something without allowing them to know anything about it. People debate things if they find them interesting, not because they're told to. I watched a first year "humanities" lesson once in which they were told to put ten statements into "order of importance". The teacher's instructions were: "It doesn't matter if you get it right or wrong, so long as you can explain your reasons". Even if writing skills was the point here, wouldn't it be more satisfying if they had some reasons to assess? That must have felt like walking on air rather than the ground. You can't ask me whether I think peace, the environment or starvation is the most important crisis on Earth without giving me some data about which is harming how many (even if they weren't all interlinked).

I wasn't at all surprised to see the footnote at the article, that Mr Grey has given up teaching. I sympathise. As for the "how science works" bit, I think that is important. But that means doing it, not talking about doing it - which, incidentally, is just what is wrong with "practical" subjects like technology nowadays, which children good with their hands but not so good at writing used to find such a relief - and the same will go wrong with these flashy new diplomas, too, now that they're "going to be more academic than A levels". Do we learn to play football by writing down the rules? You don't learn physics, or how to look after the world, by being bored out of your mind by it all at the age of 14. Hardly surprising that as soon as people get to university, they can't remember a thing they did at school, and have to start with basic algebra all over again.

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PS Am I being thick, or is the question even answerable? It doesn't give a figure Tom was originally spending, in which case how can anyone calculate the payback time? Or does "to" mean "by"?


JeffR said...

I agree, the question at the beginning is incomplete. You need to know how much he paid before installing the insulation.
To make it a physics question, they should be asked to explain how insulation works, what does it do to prevent heat loss?

weezerd said...

How to insulate a spaceman, etc.?
Well the question might end up in schoolwork if there is ever enough funding to enable the relevant subjects to be researched and included in a curriculum.
Nothing comes for free and that is most obvious in the quality of schooling of our (grand)children. But should I be going there in this forum? Tha is another subject!

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