Category: learner thinking

Because the sugar's so small it would evaporate with the water

Keith S. Taber

Morag was a participant in the Understanding Science project. In an interview in her first term of secondary school, Morag suggested that when sugar with mixed with water, it could not be separated out again. This was in the context of discussing chemical change, when she was explaining to me that a chemical change is where two things just go together:*

I: So what's a chemical reaction?

Morag: (I had to learn this) it's when two things, erm, are mixed together and can't be made to the original things easy, easily.

I: Oh, can you give me an example of that?

{pause c. 2 s }

M: Water mixing with sugar, but that's not a chemical reaction.

I: Oh so that's something else is it, is that something different?

M: I don't know.

I: Don't know, so can you mix water with sugar?

M: Yeah, but you can't get the water and the sugar back together very easily.

I: You can't. Is there a way of doing that?

M: No.

I: No? So if I gave you a beaker with some sugar in, and a beaker with some water in,

M: Mm.

I: and you mixed them together, poured them all in one beaker, and stirred them up – you would find it then difficult to get the water out or the sugar out, would you?

M: Ye-ah

I: Yeah, so is that a chemical reaction?

M: No.

The conversation went on to explore Morag's ideas about chemical reactions, and her notion that the flame reacts to the gunpowder * when a firework explodes. A little later we returned to her notions relating to mixtures of sugar and water (i.e., solutions).

I: And when you mix sugar and water, you get kind of sugary water

M: Yeah.

I: Have you got a name for that, when you mix a liquid and solid like that?

{pause c. 1 s}

I: Or is that just mixing sugar and water?

{pause c. 1 s}

M: There is a name for it,

I: Ah.

M: but I don't know it.

I: Okay, so when we mix it we get this sugar-water, whatever, and then it's harder to, it's hard to separate it is it, and get the sugar out

M: Yeah.

I: and the water out?

M: Yeah.

As I probed further, I elicited a difference that Morag perceived between water/sugar mixture (solution) and water/salt mixture (solution). At the time I was not sure what to make of this, and feeling that Morag was probably to some extent searching for answers on the spot, decided to move back to other themes. However, in retrospect, Morag seems to be saying there is a difference because in some sense the sugar is smaller, and so on evaporation can be taken away with the water – unlike the case with salt (solution). Her explanation is vague, but she refer to water:salt ratio, so appear to mean how much can dissolve rather than thinking in terms of molecular size.

I: So is that a chemical reaction?:

{pause c. 3 s}

M: No.

I: No, is that a chemical change?

{pause c. 3 s}

M: Yes.

I: Ah, okay. So what's the difference between a chemical change and a chemical reaction?

M: A reaction is where two things react with each other, like the gunpowder and flame, and a change is where two things just go together. You know like water and sugar, they go together like water and salt. Partially, they go together.

I: Mm. Partially?

M: Yeah. 'cause, erm, in water and salt you can get the salt back, whereas you can't with water and sugar.

I: Oh, so it's different, is it? Oh, I see. So if you had water and salt, how would you get them back again?

M: Erm, you'd put the water and salt by the window, and let the sun do all the evaporating of the water, and you would be left with the salt crystals.

I: So what if you took water and sugar, and put that by the window, would it evaporate the water, and leave you with the sugar?

{Pause, c. 1 s}

M: N-o.

I: That's different then, is it?

M: Yeah, cause the water's absorbed kind of like the sugar, and because they're, it's so small it would just take the sugar with it.

I: What do you mean it's so small?

{Pause, c. 1 s}

I: What if I had a big beaker of water and sugar?

{Pause, c. 2 s}

M: But there would be more water to salt ratio.

I: …Okay, so there is a difference, then, there's a difference

M: Yeah.

I: between the sugar and the salt?

M: Yeah.

This is an unsatisfactory place to leave the discussion, and in hindsight there are questions I would like to have asked. (Why did she think she could not recover sugar by leaving the water to evaporate? Was she thinking of the amount of sugar / salt needed to form what we would call a saturated solution?…)

Plants store sunlight

Keith S. Taber

Bill was a Y7 student participating in the Understanding Science project. He 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

So Bill did not make the connection between storing energy, and what he interpreted from his science lesson as 'storing sunlight'. This appears to be an example of a fragmentation learning impediment.

An element needs a certain number of electrons

An element needs a certain amount of electrons in the outer shell

Keith S. Taber

Bert was a participant in the Understanding Science project. In Y10 Bert was talking about how he had been studying electrolysis in class. Bill had described electrolysis as "where different elements are, are taken out from a compound", but it transpired that Bert thought that "a compound is just a lot of different elements put together"*. He seemed to have a tentative understanding that electrolysis could only be used to separate elements in some compounds.

if they're positive and negative then they would be able to be separated into different ones.

So some things are, some things aren't?

Yeah, it matters how many electrons that they have.

Ah. [pause, c.3s] So have you got any examples of things that you know would definitely be positive and negative?

Well I could tell you what happens.

Yeah, go on then.

Well erm, well if a, if an element gives away, electrons, then it becomes positive. But if it gains, then it becomes negative. Because the electrons are negative, so if they gain more, they just go a bit negative.

Yeah. So why would an element give away or gain some electrons? Why would it do that?

Because erm, it needs a certain amount of electrons in the outer shell. It matters on what part of the periodic table they are.

Okay, let me be really awkward. Why does it need a certain number of electrons in the outer shell?

[Pause, c.2 s]

Erm, well, I don't know. It just – 

So Bert thought that an element "needs a certain amount of electrons in the outer shell" depending upon it's position in the periodic table, but he did not seem to recall having been given any reason why this was. The use of the term 'needs' is an example of anthropomorphism, which is commonly used by students talking about atoms and molecules. Often this derives from language used by teachers to help humanise the science, and provide a way for students to make sense of the abstract ideas. If Bert comes to feel this is a sufficient explanation, then talk of what an element needs can come to stand in place of learning a more scientifically acceptable explanation, and so can act as a grounded learning impediment.

References to atoms needing a certain number of electrons is often used as an explanatory principle (the full shells explanatory principle) considered to explain why bonding occurs, why reactions occur and so forth.

Bert's final comment in the short extract above seems to reflect a sense of 'well that's just the way the world is'. It is inevitable that if we keep asking someone a sequence of 'well, why is that' question when they tell us about their understanding of the world, they eventually reach the limits of their understanding. (This tendency has been labelled 'the explanatory gestalt of essence'.) Ultimately, even science has to accept the possibility that eventually we reach answers and can not longer explain further – that's just the way the world is. Research suggests that some students seem to reach the 'it's just natural' or 'well that's just the way it is' point when teachers might hope they would be looking for further levels of explanation. This may link to when phenomena fit well with the learner's intuitive understanding of the world, or tacit knowledge.

Bert's reference to an element needing a certain amount of electrons in the outer shell also seems to confuse description at two different levels: he explicitly refer to substance (element), when he seems to mean a quanticle (atom). Element refers to the substance, at the macroscopic level of materials that can be handled in the laboratory, whilst an atom of the element (which might better be considered to gain or lose electrons) is part of the theoretical model of matter at a submicroscopic level, used by chemists as a basis for explaining much macroscopic, observed behaviour of samples of substances.


Because they are laws these things have to be true

Keith S. Taber

Ralph was a participant in the Understanding Science project. When I interviewed him in Y10 he suggested that what was particular to science was that with science it will always be the same, i.e., that the nature of science was that it was universal rather than relative to a particular place. Ralph had commented that "because they're kind of like, they are laws so…these things have to be true".

I: So in say maths you have these laws that are what, universal?

R: Yeah.

I: And science you think is the same sort of thing?

R: Yeah.

So Ralph was asked about the universal nature of laws in science:

I: So what laws do you know in science then that will apply anywhere?

R: Erm, well there's kind of like the laws of gravity and things, which are always there. But they can, that is one exception, because that can be changed depending on what planet you are on, but that's kind of like very, far off so, if you went on the moon and did physics there it might be ever so slightly different, but I'm not sure because I haven't been to the moon though.

…

R: And chemistry it's so – reactions and things – but the environments can change those, but not to a large extent, so, so iron will always react with something, no matter what, and two of the same element will not react together because they're already the same and things like that.

I: Mm?

R: Erm, yep, and biology's because most is kind of like is an average so, it can be different as well, but they're kind of like, saying they're all universal laws and all actually the same is kind of a bit untrue, but if like, there are exceptions to the rule in different places, so biology you can kind of like have erm illnesses or disfigurements that change how you look at biology, and things, which is kind of complicated and you don't tend to do that in this kind of level of biology, 'cause that's more kind of like that's specialised, that's more in kind of medical biology and things.

I: So it's a kind of 'unless' law, so, you know, a dog will always have four legs,

R: Yeah.

I: unless one of them's been torn off

R: Yeah.

I: or unless it is a mutant and grown an extra one?

R: Exactly, unless there is some kind of other, erm, other … event which … changes how that will work, so … like a snail would normally have no legs, but if you put loads of radiation on it, I dunno, maybe it would grow an arm or something.

It seemed Ralph's notion of a law of gravity was not the universal law of Newtonian physics, but something linked to the local strength of the gravitational field. (Later in the interview Ralph explained that the law of gravity is that things will always move towards the centre, but it is different on the moon*). In chemistry, Ralph seemed to see ideas about which substances reacted together as laws, although he acknowledge that in some cases these patterns were dependent upon conditions. In biology, Ralph associated laws with the normal forms of organisms, which again he knew could be changed by environmental factors.

In general then, Ralph's notion of scientific laws did not match the scientific notion of a law, which would generally operate at a 'deeper' level (i.e., a higher level of abstraction from observations), but seemed more at the level of 'facts'.

With science it will always be the same

Keith S. Taber

Ralph was a participant in the Understanding Science project. When I interviewed him in his first term of upper secondary science he told me he was studying a range of topics in science, so I asked him what was common to these topics that made these different lessons all science.

I: So what makes that science, then, because it all seems so varied?

R: Well (Exhales) – physics is kind of like just like, distinguishing it from like, like forces and the things that we can't really see, so it's like, whereas chemistry is like big bangs and things so you can like, very visual one, and biology is like understanding the human body and things, so, I've completely forgotten what the original question was.

I: So what makes physics, chemistry and biology science, why don't we just call them three separate subjects, have they got anything in common?

R: Mm, erm. Er (Pause, c.2s, then Ralph exhales) … Erm, it's more because they're kind of like, they are laws so they kind of like effect, so these things have to be true. Whereas kind of in English and things, yeah that's fine, but they can be changed with different places, depending where you are, whereas, with science, it will always be the same. It's like maths because maths is kind of like physics and physics uses maths, because maths will always be the same wherever you go, 'cause the, you can't like, you can't say like in one place that two will equal two and in another place two will equal three or something. They've always got to be the same.

So for Ralph, a distinguishing criterion for science (and maths) was the universal nature of science: that it offered laws which "will always be the same". This is an interesting observation about the nature of science, with Ralph rejecting any relativistic notions of science, which might apply to some other subjects ("they can be changed with different places, depending where you are"). The need for scientific laws to apply regardless of context would be widely accepted, although Ralph's comments could also be seen to ignore the provisional nature of science (e.g. if laws are seen as  human constructions to interpret patterns in nature, rather than understood as given in nature).

(Although Ralph observed that because they are laws these things have to be true, when he attempted to exemplify this in physics, chemistry and biology, he was not able to suggest clear examples of universal laws in science.)

An atom is the smallest amount of matter you can get

Keith S. Taber

Mohammed was a participant in the Understanding Science Project. When Mohammed was near the end of his first term of upper secondary science (in Y10) he told me that in his chemistry lessons he had been studying atoms and ionic bonding. When I asked him what an atom was, he suggested it was "the smallest amount of matter you can get" as well as being "it's the building block of all matter". It is not unusual for students to suggest that atom is the smallest thing that one can get, and then go on to report that it has smaller constituent parts when asked about atomic structure! Mohammed justified his suggestion that an atom was "the smallest amount of matter you can get" by excluding individual subatomic particles from being considered matter:

I: So – if I ask you, what's an atom?

M: It's the smallest amount of matter you can get, it's the building block of all matter.

I: So you can't get anything smaller?

M: No. If, if you – if I, let's say, took the electrons away, then it wouldn't be matter any more.

I: What would it be then, then?

M: It would just be a nucleus.

I: So, if we have got an atom, and you take the electrons away, that would seem to be smaller than the atom? But you are saying it is not really matter any more, it does not count as matter.

M: Yeah.

I: So how do we know what's matter? What's matter?

M: Matter is something that is built out of protons, neutrons and electrons.

I: Ah, so it has to have all three?

M: Yeah.

So from Mohammed's perspective it would not necessarily have been inconsistent to suggest that an atom was the smallest particle of matter possible, despite it having structure, if the definition of matter included suitable criteria. However, Mohammed did not suggest that, for example, matter had to have overall neutrality, and his suggestion that matter is something that is built out of protons, neutrons and electrons had to be amended when it was then tested out. He maintained, however, that if you take all of the electrons off an atom, then you would stop having matter.*


A sodium atom wants to donate its electron to another atom

Keith S. Taber

Lovesh was a participant in the Understanding Chemical Bonding Project, studying 'A level' chemistry in a further education college. He was interviewed in his second year of the two year A level course, and was presented with focal figure 1 (below). He recognised figure 1 as showing a "sodium, atom", and was asked about its stability:

Is that a stable species, do you think?

Erm (pause, c.3s) No, because it hasn't got a, a full outer – electron shell, outer electron shell hasn't got eight electrons in.

Lovesh shared the common notion that an atom without a full outer shell / octet of electrons would be unstable compared with the corresponding ion with a full outer shell / octet of electrons. When comparing isolated atoms with the corresponding ions this is seldom the case, yet this is a common alternative conception about chemical stability. A sodium ion can be considered stable in an ionic lattice, or when hydrated in solution, but does not spontaneously ionise as the outer shell electron is attracted to the atom's positive core. Ionisation only occurs when sufficient work is done to overcome this attraction.

Lovesh was demonstrating the common full shells explanatory principle alternative conception which is central to the common octet rule framework – an alternative conceptual framework reflecting very common 'misconceptions' found among learners studying chemistry.

Lovesh was asked what would happen to the atom that he considered unstable:

So if it's not stable, what would tend to happen to that, do you think?

It will wanna donate the electron to another atom.

Right, when you say 'it wants to donate' it?

Erm. (pause, c.3s) Well because that outer electron is less attracted to the nucleus, erm it is, it can easily be transferred, attracted by another atom.

Lovesh's first response here used the term 'wanna' (want to) which if take literally suggests the atom has desires and preferences. This is an example of anthropomorphism, imbuing objects with human-like traits. Using anthropomorphic explanations is a common feature of the octet rule framework which often leads to students talking as if atoms deliberately act to get full outer electron shells.

It has been suggested that such anthropomorphism may be either 'strong'- where the learner is offering an explanation they find convincing – or 'weak' if they are using language metaphorically, just as a figure of speech.

In this case, when Lovesh's use of the notion of 'wants' was queried he was able to shift to a different language register in terms of the action of physics forces – the electron being attracted elsewhere. Lovesh had clearly acquired an appropriate way of thinking about the interactions between atoms, but his spontaneous explanation was couched in anthropomorphic terms. Although in this case the anthropomorphism was of a weak form, the habitual use of this kind of language may come to stand in place of offering a scientifically acceptable account.


A double bond is different to a covalent bond

Keith S. Taber

Annie was a participant in the Understanding Chemical Bonding project. She was interviewed near the start of her college 'A level' course (equivalent to Y12 of the English school system). Annie was shown, and asked about, a sequence of images representing atoms, molecules and other sub-microscopic structures of the kinds commonly used in chemistry teaching. She was shown a representation of the resonance between two canonical forms of the ethanoate ion, sometimes used to imply the delocalisation of the ionic charge across the COO- grouping.

Focal figure (13) presented to Annie

Any idea what this is?

They're organic compounds. And one's an inversion of the other.

Any idea what that arrow means in the centre of the page?

Does it mean that if you turned either of the, the O-minus, or the O that's double bonded around then you'd get the other compound? And it's exactly the same for that one if you turn that around, and you'd get, so it's like a reversible (pause, c4.s) thing.

Now what did you say about double bonded, what's this about being double bonded?

The oxygen is joined on the carbon with double bonds.

So what's a double bond? Is that, is that, you talked about covalent bonds earlier. Is a double bond the same as a covalent bond, or different to a covalent bond or?

Different.

So are there any covalent bonds, – the top one for example – are there any covalent bonds there?

Yeah.

How many covalent bonds are there?

Five.

And how many double bonds?

One.

And are there any ionic, ionic bonds?

No.

So we've got five covalent and one double.

Yeah.

Annie recognised the presence of a double bond (C=O) in the canonical forms shown, but seemed to see 'double bond' as an additional category of chemical bonding, different to covalent bonding, rather than referring to a particular type of covalent bond. So for Annie, each canonical form contained five covalent bonds (3H-C, C-C, C-O) and one double bond (C=O).

As the interview proceeded, Annie also suggested that single bonds are different to covalent bonds or ionic bonds.

Electrical resistance depends upon density

Keith S. Taber

Amy was a participant in the Understanding Science project.

Amy (Y10) suggested that a circuit was "a thing containing wires and components which electricity can pass through…it has to contain a battery as well". She thought that electricity could pass through "most things".

For Amy "resistance is anything which kind of provides a barrier that, which the current has to pass through, slowing down the current in a circuit", and she thought about this in terms of the analogy with water in pipes: "we've been taught the water tank and pipe running round it… just imagine the water like flowing through a pipe, and obviously like, if the pipe becomes smaller at one point, erm, the water flow has to slow down, and that's meant to represent the resistance of something".

So for Amy, charge flow was impeded by physical barriers effectively blocking its way. She made the logical association with the density of a material, on the basis that a material with densely packed particles would have limited space for the charge to flow:

So electricity would "not very easily" pass through a wooden bench "because wood is quite a dense material and the particles in it are quite closely bonded".

In air, however, the particles were "not as dense as a solid". When asked if that meant that electricity can pass through air quite easily, Amy replied: "yeah, I think so".

Amy's connection between the density of particles and the ease with which charge could flow is a logical one, but unfortunately involves a misunderstanding of how charge flows through materials, i.e., from a canonical scientific perspective, thinking about the charge flowing through gaps between particles is unhelpful here. (So this can be considered an alternative conception.) This seems to be a creative associative learning impediment, where prior learning (here, the spacing of quanticles in different materials) is applied, but in a context beyond its range of application.


A dusty analogy – a visual demonstration of ionisation in a mass spectrometer

Keith S. Taber

Amy was a participant in the Understanding Science project. She was interviewed when she had just started her 'A level' (i.e., college) chemistry, and one of the topics that the course had started with was mass spectrometry. She gave me a very detailed account of what she had been taught, despite both casting doubt on the logic of parts of the account, and of the accuracy of her own recollection (see Amy's account of mass spectrometry *). One of the unconvincing aspects of the new topic seemed to be the way positive ions were produced by bombarding atoms with (negative) electrons – although she had clearly picked up the point.

She reported that her teacher had demonstrated this point with an analogy. She told me that the teacher was using a lot of analogies, and she seemed to find them a little silly, implying that this analogy was not helpful. This particular example involved a board duster and two matchboxes. One matchbox sat on the duster, and was knocked off by the other matchbox being projected at it.

I thought this was quite interesting, as Amy did think the formation of positive ions was counter-intuitive, but had remembered that this is what happened, and seemed to both remember and understand the use of the analogy – even though she was somewhat dismissive of it. I didn't get the chance to explore the issue at the time, but wondered if this was an example of a student maybe not appreciating the role of models and analogies (and simulation) in science itself, and so feeling that using such a device in teaching science was a little 'naff'. 

Amy's explanation of the stupid-sounding bit

Amy was dismissive of the teacher's analogical teaching model, even though she seemed to have remembered what he was illustrating:

I mean there was a couple of bits there that you didn't seem too sure about like, like er you know you sort of, you seemed to almost disown the fact that this electron gun is going to make these things into positive ions, you didn't seem very convinced by that?

Erm – I dunno if it's that I'm not convinced it just sounds weird, because it's like erm (pause, c.2s) I dunno, well it's like it's not something which you can see,

No.

and it's like, I dunno, he did this sort of example using a duster and two matchboxes, and, which wasn't very good, so.(Amy was laughing at this point)

Tell me about that then, how does that work? You see I know a bit about this, I don't know about the duster and the matchboxes.

Like no disrespect to our teacher but he uses these analogies, a duster being an atom with matchboxes being the electrons and something, and them being knocked off, because, yeah.

So he threw a matchbox at a duster that had a matchbox and he knocked the matchbox off the duster?

Pretty much.

See, it works for me,

(Amy laughs)

and you've remembered it?

Well, yeah, but – yeah.

…

Erm, So you've got this neutral atom, and you're firing negative electrons at it?

Yeah.

Now if you say that to somebody who doesn't know anything about what's going to happen, what do you think might happen if you fire negative electrons at a neutral atom?, what might you get?

A negative ion.

That's what you'd expect I think, isn't it, … well obviously you are firing negative things at it, so you will get negative. But in fact that's not what seems to happen. So he was trying to explain to you why firing negative things, at something neutral, you might end up with something positive. 'cause that's not obvious and logical, is it?

Yeah.

So if you throw a matchbox at a duster that contains a matchbox, you might knock the match box off?

Yeah (Amy laughs).

There is clearly a 'cultural' difference here, between the interviewer (a science teacher by background) and the interviewee (the learner), in that the interviewer 'got' the use of the demonstration as a pretty neat physical analogy, whereas the student clearly was dismissive. In this case Amy's lack of engagement with the modelling process did not seem to limit her learning, but her attitude demonstrated a lack of awareness of the status and roles of models in science (and in learning science) which has potential to act as a deficiency learning impediment if she cannot see how teaching models and analogies can help form mental models of scientific systems.

A theory is an idea that can be proven

Keith S. Taber

Adrian was a participant in the Understanding Science project. When I spoke to him during the his first year (Y12) of his 'A level' course he told me he had been studying quantum theory, and I asked him about the name 'quantum theory'.

So why do we call it the quantum theory because that is an unusual name isn't it?

I don't know.

No?

No.

What's a theory?

An idea that can be proven? Yes.

A modern understanding of the nature of science does not considered that theories are the kinds of things that can be proved in any simply and straightforward sense. Widely accepted theories are usually supported by a good deal of evidence, and individual components of them may be subject to experimental testing, but a theory as a whole can not be proved as such.

I wanted to find out what scientific theories Adrian was familiar with:

Give me an example of a theory you are familiar with?

I'm familiar with?

Yes. Apart from the quantum theory what other theories do you know?

Pythagoras's theorem.

Okay.

It's completely different, which is basically is a squared equals b squared plus c squared…What other theories, erm… I'm not sure.

So Adrian's only other suggestion of a theory was actually a mathematical theorem (which could be logically deduced within a particular system of axioms, unlike a scientific theory which refers to some aspect of the natural world).

I suggested the theory of evolution that Adrian should have met during his secondary science course earlier in the school: but Adrian claimed he was "not familiar with it" asking if it was "e=mc²"(Is the theory of evolution e=mc²?). Adrian recognised this as a formula, but thought that counted as a theory,

Tell me about e=mc² then because I am teaching that this afternoon so… I am teaching that subject this afternoon, so tell me about that, I need to know about that.

It's a formula. I am not sure that it works out, I am not sure that I understand it, was it Isaac Newton I think sort of come up with the theory. I have never used it and I don't know what you would use it for. …

You think that might be a theory as well?

Yes.

and the theory is an idea that can be proven?

Yes.

Yes. So do you think the various theories that scientists have come up with over the years have been proven?

Yes, but some would have limitations to where they can be sort of – How they can be used if that makes sense.

So they have got a kind of range of applications?

Yes.

A protein is something which is used for growth and repair

Keith S. Taber

Amy and the role of proteins: a slogan – "proteins are needed for…"

Amy was a participant in the Understanding Science project. Amy was in her first term of 'A level' biology. One of the things she was studying was proteins:

"because proteins do lots of things…they're used for growth and repair, and they form different things like apparently [sic] insulin is a protein"

Amy admitted to be surprised that insulin, which was "made in the pancreas which controls blood glucose levels" should be a protein. She had not expected this "just because you were never told". She has also now learnt that "apparently [sic] haemoglobin is a protein". Amy explained that

"it's just cause like, up until GCSE you're just told that like you know a protein is something which is used for growth and repair, and not that it can be used to make sort of something like insulin"

It seems that at GCSE level (i.e., up to age 16) Amy learnt a slogan relating to the role of proteins – proteins are needed for growth and repair, but a slogan that only related to a processes, without any suggestion of how this might relate to materials and structures. Insulin is considered to be linked to (processes of) sugar regulation, and haemoglobin to (processes of) supplying cells with oxygen. Neither of these processes are seen as growth or repair. It seems 'repair' is primarily understood in terms of damage at the level of tissues, not individual cells or molecules.

This could be considered as an example of a fragmentation learning impediment – the student has not made the link. However, if her school teaching was in terms of the slogan 'proteins are needed for growth and repair', then this could also be seen as a pedagogic learning impediment (a type of grounded learning impediment), as that way of teaching gave Amy a way of thinking about the roles of protein in the body which did not make her receptive to learning that molecules such as insulin and haemoglobin might be proteins.