Keith S. Taber
Morag was a participant in the Understanding Science Project. During her first term in secondary school, Morag told me she had studies changes of state, which was about "melting things, it's like solid, liquid and gas. Where like an ice cube melts to go to water, it evaporates to go to gas, it then condenses to go to water and then freezes to go to ice".
When I asked her about about the states of matter, Morag gave me a quite polished response. In the middle of this, she stood up and started moving about. It appeared that she had modelled the states of matter in class through a simulation, with the students acting as particles – and this association seemed to now be cued by her recalling the explanations for the different states of matter:
I: So silly question, 'cause I'm sure everybody knows really, but what's a solid, what's a liquid and what's a gas then?
Morag: A solid is an object where the particles are very close together, but still have room to move very slightly, you know like they can only move little bits, er, it has a fixed shape, it cannot be poured – and that's all I can remember.
I: That's quite a bit. And that's different to a liquid, is it?
M: Yeah, 'cause a liquid you can pour, it takes the shape of its container, the particles are spread out more evenly, but still in a, but are still spread in a – yeah they're spread evenly it can be poured, (it takes the shape of its container), the particles are still quite close, but they are further away than they were in a solid, so they can move just a bit more. If you know what I mean, like. So if someone was stood here [indicating next to her], we'd be a solid, 'cause we just move very slightly,
I: all right, yeah
M: and if we were a liquid we would be stood just a bit further away, so we can move a bit more.
I: I see, so if you had brought a friend with you,
M: Yeah, and if we were stood like that, if she was stood there, we'd be a solid, 'cause we were quite close, but we still had room to move about
I: Mm
M: if we were a liquid, we'd be a bit further, but we still, still quite close, but still had move to room, to move about, and I'm not going to tell you about gas until we get onto gas.
I: Okay. So you and your friend could be a liquid? Which means that I could pour you and you would take up the shape of your container?
M: No, I mean like we'd be the particles in liquid.
I: Ah, I see.
M: you know like
I: Moves around!
M: like, so like, like, so we'd be like that, and there would be lots of us, but we could still move about. Yeah? And if we were a liquid we would be like that, and we could still move about. And if we were a gas we'd be further apart, but and then we can, and then we can move around the room freely.
