Monday, 11 March 2013

Update on Energy

In my ongoing love-hate relationship with the concept of energy, I returned to the subject during a CPD session I ran today.

The session was for Primary teachers who have little, or no, science background.  The aim of the whole course (of which the session is but a small part) is to enable the teachers to develop a confident understanding of science up to KS3 level.  They will then be better able to support their pupils, and colleagues with primary science.

I had run a similar session before, but having read Millar's latest paper on energy, I decided that I would change things around slightly this time.

The structure was:
Introduction - what is Energy?
Answer - we're not entirely sure, but we know that it's conserved and we can do some interesting sums with it.  (The subplot of this is that as science teachers we/they don't have to know all the answers - suggested they use a question wall where they can 'park' questions).

Part 1: Food labels
We started by looking at lots food labels to get a feel for the energy contained in different foods.  We talked about the sort of sums that we could do with that information and also made diet and healthy living links.  We starting looking at 2000 kcal for an adult, and how much food was required to make that up.  We also looked at the energy density of different food types - always a bit of a shock.

(If I'd had more time, I would have burnt some food at this point.)

Food as a fuel and the linked to other types of fuel and energy resources.
This was a helpful next step, and took the flow of the session from the personal to the wider world.  I used one of the ASE Upd8 activities to look at some of the issues relating to the type of fuel to use in cars.  We then progressed to ideas about renewable and non-renewable fuels, which led naturally into David MacKay's thesis that we need to use numbers, not adjectives, to talk about consumption and generation of electricity/energy.

Part 2: how much is a joule.
An Energy Ladder
I used an 'energy ladder' to start thinking about the relative sizes of different energy stores.  This led to a sobering discussion of how much exercise we have to do to balance out the energy we receive from food.  Our unit of comparison was that it required approximately 1J to lift an apple up by 1 metre.

Part 3: Energy stores and energy stories
I then introduced the idea of energy stores, using those stores defined by the IOP in their SPT materials.  Each of these stores can be justified because there is an interesting calculation that we can carry out related to each of them - though not at KS3, or even KS4 in some cases.  Using the 'orange liquid model' of energy we looked at the energy stories of some different objects, making sure that we  carefully chose our start and end point, and didn't worry about what happened before or after that.  We also discussed the usefulness and limitations of the model.

Plenary:Telling their own energy stories.
Using different toys/items the teachers told the energy stories - choosing the start and finish points and talking about which energy stores were emptying and which were filling, and how the energy shifted between the places.

Reflections: looking at the overall structure of the session I think that it works well as it provided a coherent overarching story to the progression of energy ideas.  We did it in a short space of time, but it could easily be done as a curriculum topic.  The progression of ideas followed nicely from upper KS2 to KS3, and would extend to KS4 and the introduction of sums to calculate energy (kinetic, gravitational potential, specific heat capacity) as well as supporting the big picture of Energy post-16.