Every Big Helps

Mobile phone chargers: not big amounts of energy


Quick bit of Physics:

If you haven’t read David MacKay’s Sustainable Energy Without The Hot Air, go and do it now.  It’s great.  Partly because it’s about something important- keeping the lights (and everything else) on for future generations.  Also, it’s a really good example of something that physicists are trained to be good at; working out which factors actually matter when you are trying to solve a problem, and which ones you can quickly discard.

MacKay calls the concept “Every Big Helps“.  For example, think about mobile phone chargers left on standby.  Or rather, don’t.  Yes, there are lots of them, but the power wasted by each one is small.  Even if you multiply by the number of phones in the UK, it will still be a small total.  Better not to waste that energy, but it’s a tiny amount compared with (say) the energy consumed by cars.

I’ve been reminded of this by a couple of experiences at school in the last week.  One was a staff meeting about school policy changes for next year; things like marking and documenting differentiation.  I can’t say that the changes are bad- though a marking policy that is going to be applied and monitored across every subject is bound to be a bit clunky.  Where it bothers me is when I look at the end-of-year exams I have just marked.

The pattern is one that I suspect most teachers will have experienced.  A proportion of the group have clearly taken on board the ideas we have worked through together this year; I recognise the phrases and patterns; even the mistakes are from slightly mis-applying things we did in class.  Another proportion of the group haven’t, and have floundered.  Very few of the papers- even from those who have done well- show much sign of the school-wide tips for reading and answering exam questions that they are meant to have been practicing in every subject all year.

There are big things I can do that would help these pupils a lot.  Making sure that they always get the key facts and ideas right.  Ensuring that they check that what they write actually matches the question they are answering.  A goodish chunk of the challenge will be making sure that these pupils are on-task more of the time, and completing more work.  And I’ll continue to do what I can to do these.  But it’s about to get a little bit harder, because a few more little things have been put in the way of the big things.  And it’s every big that helps.