Bill [Year 7 pupil] told me that “solids they stay same shape and their particles only move a tiny bit”. He explained that the ‘particles’ were “the bits that make it what it is”, although “you can’t see them” as “they’re very, very tiny”. Later he commented that “they are microscopic”. He explained that “there is particles in everything”. Bill was able to talk a lot about particles in solids, liquid and gases and explain what happened during melting.
Later in the same interview Bill talked about how in his primary school he had studied “a lot about plants, and – inside them, how they produce their own food”, and how “inside, it has leaves, inside it, there is chlorophyll, which stores sunlight, and then it uses that sunlight to produce its food.”
I asked Bill if plants had anything to do with particles:

Bill: Well in the plant, there is particles.…’cause it’s a solid.… inside the stem is, ‘cause going up the stem there would be water, so that’s a liquid. And, it also uses oxygen, which is a gas, to make its food, so. I think so.

Bill explained that "…in the leaves it is chlorophyll which is a green substance, so that would make, give it its colour".

Interviewer: Do you think chlorophyll is made of particles?

B: Hm, don’t know.

So it seemed that although ‘there is particles in everything’, Bill did not seem to feel this meant that he could apply the particle idea to all substances.

Amy was a Y10 (14-15 year old) student who had separate lessons in biology, chemistry and physics. When I spoke to her, in biology she was studying respiration which she suggested was “converting glucose and oxygen into energy…through anaerobic respiration and aerobic respiration”, which involved “converting glucose into energy, glucose and oxygen into energy and either carbon dioxide and lactic acid, or just carbon dioxide. Something like that”.

In physics lessons she had been studying the topic of electricity, and she recgonised that energy was an idea which appeared in both topics:

Interviewer: “the work in physics on electricity and the work in biology on respiration, is there any connection there?”

Amy: “Well in respiration energy is produced, and in physics energy is stored in a battery or a power supply and that then travels round - the circuit.”

When I spoke to her some weeks later Amy repeated that respiration was “converting oxygen and glucose into energy and carbon dioxide”. She told me that this was important  “because it produces energy which like in humans your body needs, well in anything, your body needs and to grow and move and things like that”. She also told me that trees were “living and they need to produce energy and when they photosynthesise they produce like energy anyway” but that she obtained energy “through food which is then erm broken down and converted into energy”.

Later in the same interview I asked her about her physics lessons, where she had been told that “there’s like different types of energy” and that it “cannot be made or destroyed, only converted”.  Amy did not seen to have recognised any issue with how she understood the role of energy in biology, and what she was taught in physics, although on further questioning he seemed able to recast her biology knowledge to fit what she had been taught in physics:

I: So in physics, they tell you [that] you cannot make or destroy energy.

A: Yeah.

I: And in biology, they tell you that you can make energy from oxygen and glucose?

[No response – Pause of c.2 seconds]
 
I: But only in biology, not in physics?

A: Oh, erm, I suppose the energy, erm well in respiration, erm the energy must be converted from stored energy in food.

Bill [year 7] used the idea of energy in talking about some aspects of his science. So when considering melting “the particles in [a solid], would have the energy, to move about more, and then it would melt down, because of its melting point, and go into a liquid”. Although he could not explain what energy was, he knew “it gives something - the energy to move, it will make something else move or something”. He remembered having done some work “ where we had to make elastic band powered, ’cause the elastic band stored the energy to make it move”, so energy could be stored.

Bill also told me about how in his previous school “we did a lot about plants, and – inside them, how they produce their own food”. He explained that “inside, it has leaves, inside it, there is chlorophyll, which stores sunlight, and then it goes, then it uses that sunlight to  produce its food. It also uses water from the roots, and the soil, and oxygen in the air. So it needs sunlight, oxygen and water to make its food and live.”

However, Bill did not relate this process to the notion of energy, and see that the ‘storing sunlight’ might have been like the energy stored in an elastic band:   

Interviewer: We were talking about energy just now.    

Bill: Yeah   

I: Do you think that’s got anything to do with energy? That process you just talked about?   

B: Hm, erm, [pause, c.3 seconds] I’m not sure

Alice and induction: Alice (17 year old A level student) saw NaCl as a molecular structure, and explained the integrity of the solid in terms of “strong enough … intermolecular forces holding things together”. She suggested that these forces might be “van der Waals’ forces” which were where,
“you’ve got if you like an electron cloud between, surrounding … each molecule, and as these clouds don’t stay in one fixed place, there’s always going to be erm sort of momentary areas of dipole. And that’s where you get your positive and negatives attracting each other again.”
So in the context of intermolecular bonding, Alice discussed how neutral species could be attracted due to induced dipoles. However, she did not consider a possibility along these lines to explain how the charged balloon could somehow have an attraction with a neutral wall. Here the potential linkage was missed.

The first time I talked to Amy, near the start of her GCSE course in Y10  she told me that “in normal chemistry [chemistry part of double science] we’re doing about ionic bonding” which was “atoms which have either lost or gained electrons so they are either positively or negatively charged” and “how the outer electron’s transferred…to complete the outer shell of the erm chlorine, thing, ion…and the sodium atom loses erm one electron, is it, yeah one electron, erm which the chlorine atom gains, and that erm, yeah that completes its outer shell and makes the sodium positively charged and the chlorine negatively charged”. Bonding was “where one thing is joined on to another thing, and it can be chemically bonded”. Although Amy did not use the term covalent bonding,  she told me that “in chemical bonding, erm like in a compound, where erm - two or more elements are joined together, that’s an example of chemical bonding, but in ionic bonding it’s the erm electrons that are transferred, I think.”

In year 11 when she was studying fats she talked about “ how they’re made up and like with all the double bonds and single bonds”  where a double bond was “where there are kind of like two bonds between erm carbon atoms instead of like one” and a bond was “how two atoms are joined together”. Later in Y11, Amy told be that she did not know how to explain chemical bonding, but “in lessons like we’ve always been shown these kind of – things – where you kind of, you’ve got the atom, and then you’ve got the little, grey stick things which are meant to be the bonds, and you can just – fit them together.” As she had told me everything was made of atoms, I provocatively asked her if the chemical bond was made of atoms. Amy had “absolutely no idea” but she “suppose[d] it would have to be, wouldn’t it”.

Later in the year I asked her why ice melts readily, but iron does not, and she suggested that “maybe the bonds between the particles stronger or something”. I asked her about the models she had used in class to show structures: “the little stick things are like the bonds between the atoms holding it together. I asked her what a chemical bond was, and she told me that “I don’t know, I don’t have a clue”. I asked her if she remembered talking to me about ionic bonding , back at the start of her course. Amy’s class “were revising something like that, but, isn’t that something to with like when an atom like gives away an electron or, no that’s completely different isn’t it?”. I asked if that had anything to do with chemical bonding. Amy did not know, and “I can’t see the link”. She remembered that covalent bonding was “where atoms would like share in electrons or something to get a full outer shell”. I asked if this had anything to do with the lines we had drawn as bonds in diagrams of structures she had been studying. Amy “I guess[ed] there is, because you mentioned it, but … I can’t see how”. She told me “it’s never, it like, in lessons it’s never been linked, like that, it’s just like one separate topic, and another separate topic.” So she had been working in class with models and diagrams that had sticks and lines as bonds, and their roles was “to hold the molecule together”, but she did not link this with having been taught about covalent bonding, something “we did it years ago”.

Sophia (a Y8 pupil) had been learning in class about different kinds of rock, including rocks that errupt form volcanoes, rocks that are formed underground, and rocks that 'come from mountains':

Sophia: When rocks … come from mountains, they like get worn away.

Interviwer: Mm, so what happens when you wear away the rock then?

S: Does it go like into a river, like a spring, and then gets carried – down, and gets smaller.…when it gets tiny, tiny would it turns into sand?

I: And then what happens to the sand, it just stays as sand does it?

S: Prob¬ … Yeah. …

I: Have you heard of a kind of rock called sandstone?

S: Yeah.

I: Any idea, what sandstone is?

S: It’s sand like, on the rock, it just looks like it’s made out of a load of sand stuck together.

Despite having been taught about the three categories of rock formation, Sophia had apparently only remembered the erosion stage in formation of the sedimentary rocks. Sandstone looked like it was made of a lot of sand stuck together, but for Sophia this seemed to be little more than a coincidence. She did not make the expected connection.

Jim, a Y7 pupil, made a distinction between turning material into a gas, and vaporising it:

KST: So if you had a metal like copper…and it melted, were there particles in the metal before it melted?

Jim: Yes.

KST: So what happened to the particles when the metal melted?

Jim: Well some of them will probably, vaporise, no, not vaporise. Erm, turn into like gas, and some of them will just turn into liquid, usually when you are burning something, some of it turns into a gas.

KST: When you say ‘not vaporise’, what’s the difference between vaporising, and turning into a gas?

Jim: Well gas is still there, when you vaporise something it totally disappears, nothing left of it.

KST: So if you vaporise something, where does it go, if it completely disappears?

Jim: Er, don’t know.

Young children commonly see evaporation as leading to material 'disappearing', The distinction between disappearing in terms of no longer appearing to be present and in terms of no longer bring present, is highly significant from the sciecne teacher's perspective. However, rather than suggest young pupils have the wrong meaning here, it might be more appropriate to suggest they simply don't see (pardon pun) an issue. Jim had learnt about the particle model of matter, and seemed to accept fully that gases are material, and consist of particles, He could talk about materials being tunred into a gas, which would have particles. Yet he seems to have also retained a distinct notion of material disappearing (in the sense of no longer being present), to which he associated the term vaporisation.