20 June 2010 at 12:26 #25186
I found actually sitting down and doing the energy workshop really useful. The bit with the pouring the coloured water into the different glasses was particularly memorable.
Is there a chance, though, that that would cause an issue for a disengaged teenager? Having spent a good bit of time at the board trying to convince them that energy is not a ‘thing’, not matter, but just a useful way of calculating things, is this practical just going to send them back to the calorific model of energy, where they conceive of energy as a substance that literally flows from one place to another?
22 June 2010 at 12:41 #25187
The “thinginess” is an issue – I think best dealt with by emphasising the re-imagining / redescription – so separating out the physical description from the “how much energy” calculation.
“What we’re doing here is calculating how much – but as we cannot yet od the calculations – to help you think about how much I’m going to show you something to help you picture this – and it’s a very useful picture”. Actually I suppose its a functional analogy (= model!) for the calculations we do, rather than a representational picture of the thing in itself.
There is more to read here:
Posting this link is really why I came here…
22 June 2010 at 16:35 #25188
[this is a copy of my post to that group, just to round this thread off]
Regarding how we avoid students thinking, I got quite a nice answer during the workshop actually. The presenter pointed out that with forces, no-one thinks that forces really are arrows [now there’s an interesting research project in its own right…] so students should be encouraged to view this very much as an abstraction.
If that is the case, is this a situation where a computer screen (like a mobile phone battery symbol) actually provides a better representation than a beaker of coloured water?
Or perhaps even a worksheet with bits to colour in?
3 September 2010 at 10:30 #25189
The whole started with the computer screen – effectively keeping it simple, and with a minimum of 3D ness, so that the quantification of energy looks more and more like juts a bar chart – you may notice the creeping simplification as you look into the first topic of the 14-16 materials. The orange water came later. Both just stand for (so give you a mental representation of) a certain calculated quantity.
Physics acquires a more austere beauty as you move on!
There again, there hints in the literature over the years that “seeing energy as a fluid” in early studies is kind of inevitable – I am just not sure that anyone went for it as we have done in SPT. The inevitability might arise because the alternative is to spend so much time telling people how they cannot think of energy, that they end up mentally paralysed. This is a kind of caricature, but as with all cartoons, I think an element of truth lies there.
I think there is a PhD on forces out there – concentrating on pushes and pulls, but I’ll leave it to the author to promote that.
But there again may textbooks write as if finding the arrows / forces is simply a matter of looking. It ain’t. You need to re-imagine the world.
3 September 2010 at 16:07 #25190
I suppose in the end it’s a thing that every model is just a model of the thing it represents. As long as the person using the metaphor knows where the pitfalls in the model might be, and looks out for these arising (rather than forewarning the students? I thibk that’s your point.) then it’s fine to use it.
You just have to think of all the representations of electrical circuits to see where this could go…
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