Energy Stores and Pathways

Tonight’s #asechat will involve Charles Tracy, the IoP’s Head of Education (and one of my bosses), discussing the new approach adopted by exam boards from this year. There’s lots of information at Supporting Physics Teaching, which is free to access and needs no sign-in. Other sites and resources will hopefully move over to this terminology (BBC Bitesize already has, for example). But why should we bother?

Energy is one of those topics, isn’t it? We teach it several times, but the kids seem to hang on to their misconceptions. Partly this is because it’s a word which is used in everyday life, often interchangably with power. Partly it’s the way students get mixed up with energy ‘resources’ (or as I prefer to teach it, ‘ways to make electricity’.

We shouldn’t be surprised that this causes problems. Energy is at heart a very abstract concept, and so one which is difficult for students to grasp. Does it make things happen? Well, not always – and this leads to students confusing energy with force. I used to divide the ‘types’ of energy into potential and moving categories, which I suppose could be seen as a crude version of this new approach.

In the simplest possible description, energy is about bookkeeping or currency. It turns out that when objects interact, often via forces, then we can do some maths which describe the change. What’s interesting is that if we pay attention, then the same number comes up more than once. This tells us that something is conserved.

We call that something energy and say it has been transferred from one place to another. Calling those places stores emphasizes that they still have whatever they were given. This sounds similar to past approaches but avoids the idea of distinct ‘chemical energy’ being turned into ‘electrical energy’ and so on. SPT has a good comparison.

So we teach energy concepts to make it easier to do calculations. We can’t measure energy directly, but the equations we use allow us to make measurements, which allow us to make deductions, which in turn allow us to make predictions.

That sounds a lot like science, doesn’t it?

Energy moves from one store to another via pathways. These are actions – verbs, if you like – which describe a change in a system. The IoP is suggesting using the word shift rather than transfer. (I would suggest one good reason to do so is to avoid the mix up with transform, which suggests there are different kinds of energy.) I found the diagram of possible pathways at SPT useful.

Several approaches are possible, including taking a ‘snapshot’ before and after an event, or showing the amount of energy in each store with orange liquid. There are of course others, many of which are visual and so provide an anchor for students to observed reality. This isn’t to recommend VAK of course – only to suggest that making this concept ‘stract’ can only be a good thing.

I’ll be taking part in the session this evening, and I’ll add a link to the archive afterwards. I’m sure there’ll be an advert for TalkPhysics, which is one place to get access to ongoing advice and support on this and other approaches. It may be short notice but please pass on the link for tonight’s chat; the more the merrier.


My Utility Belt

This was already planned as a response to Ian McDaid’s What’s In My Bag post, but I was prompted by a tweet from Cory @Doctorow about the wonderful Grid-It organiser. They’re great. Go and buy one.

So anyway, here’s the contents of my bag, about to be packed ready for my induction tomorrow into the Hall of Fame. I mean, Justice League. Okay, it’s actually into the Stimulating Physics Network, but that’s honestly nearly as good. Just with less lycra.



Starting at the top left:

  • Moleskine 18 month planner, hacked with elastic to hold a pen (Leuchtturm1917 make one if you don’t have the bits handy) and with plastic tabs to save time. Hint: Stick a few post-its in the back for convenience.
  • Decent ballpoint which stays put and a keep-in-my-pocket Uniball fineliner. These are 5 for £4 in Tesco at the moment, go and buy some quick.
  • Pencil case, bought for me. Filled with, well, pens and stuff.
  • Elephant Wallet, basically some elastic sewn together to make a great minimalist wallet. Made to order, tiny in your pocket.
  • Earbuds for podcasts, music and blocking out the world when on a train. Cheap because I’m always losing the damn things.
  • Small notebook with detachable pages in a leather sleeve, bought on sale at a silly price from Waterstones. I am a bit of a stationery nerd.

The electronics:

  • Nexus 2013 edition, shiny gadget running Android. For once I was an early adopter with a Samsung Tab, but this is lighter and faster. And half the price of an iPad mini. Small enough to hold in one hand (great ebook reader) but has a big enough screen to make working possible.
  • It’s stored in a Cocoon Grid-It, basically a neoprene sleeve with loads of elastic across it. You can stick an amazing amount of stuff in there (currently: two sets of business cards, spare pen, painkillers, cables, book of stamps, coffee disloyalty cards, ruler, worked flint tool from 10k years ago, memory stick) and it all stays put.
  • To make the tablet a bit more practical, add a Bluetooth keyboard. There are loads about but it means you’ve got a kind of DIY netbook. I’m not linking to this because it’s acting up, but that’s possibly me.

So there we are – add in my phone (cheap android, tethers the tablet when needed, and what I used for the photo) and we’re done. All in a bag that I forgot to take a picture of, but it’s a rucksack because I have delusions of youth. Briefcases are for grown-ups and satchels are for schoolgirls in Enid Blyton books.

More posts coming soon, but I need to sort out what the rules are going to be for sharing resources on here. Hope everyone has had (or is about to have) a great start to the new school year.