Fuels get used-up when we burn them

Keith S. Taber

Sophia was a participant in the Understanding Science Project. Sophia (then in Y7) had been burning materials in science. She had burnt some paraffin in a small burner (a glass burner with a wick). Her understanding of the process was not in terms of a chemical reaction, but at a more 'phenomenological' level:

So what happens to paraffin when it burns then?

It keeps on burning… but you, you can put it out easily as well…. we just blew it out…

I see, but otherwise it just carried on burning, did it? Did it carry on burning for ever, if you don't blow it out?

No, 'cause it would run out.

What would it run out of?

The paraffin.

So where does the paraffin go then?

(There was a pause, of about 4 seconds. Sophia laughs, but does not offer answer.)

And what happens to the level of the paraffin in the burner?

It gets lower and lower.

So why's that, what's happened to it?

'cause you are using all of it up, when it's burning.

So it get all used up does, it – so what happens when it's all used up?

You have to refill it.

So for Sophia the burning of paraffin is not seen in terms of basic chemistry (what happens to the substance paraffin during the process of burning?), but rather she seems to interpret what she has seen in terms of everyday ideas – stuff, such as fuels, get used up – if we use it, we no longer have it.

The final question in this sequence ('what happens when it's all used up') is not treated in scientific terms (e.g., from the perspective of the conservation of matter, there is an issue of where the 'stuff' what was the paraffin has gone), but in practical terms: when we use up the fuel in the burner, we need to refill it to do more burning.

Here, understanding in 'everyday' or 'lifeworld' terms seems to dominate her thinking: the familiar idea that things get used-up obscures the scientific question of what happens to the matter in the fuel. Presumably, her teacher wanted her to focus on the scientific perspective, where burning is combustion, a type of chemical change, but it appears her life-world perspective acted as a grounded learning impediment – an existing way of thinking about a phenomenon that is taken for granted and obscures the scientific perspective.

The everyday way of understanding the world could be called the natural attitude. It seems that for Sophia it is 'just natural' that fuels get used up, and so there is nothing there to explain. Arguably, the work of a science teacher sometimes involves persuading students to seek explanations for things they had considered 'just natural', and so not in need of explanation.

Energy cannot be made or destroyed (except in biology)

Keith S. Taber

Energy can be made, but only in biology: Amy had learnt that respiration was converting glucose and oxygen into energy – but had learnt in physics that energy cannot be made

Amy was a participant in the Understanding Science Project. Amy was a Y10 (14-15 year old) student who had separate lessons in biology, chemistry and physics. When I spoke to her (see here), she had told me that respiration was "converting glucose into energy and either carbon dioxide and lactic acid, or just carbon dioxide". When I spoke to her again, some weeks later, Amy repeated that respiration was "converting oxygen and glucose into energy and carbon dioxideit produces energy" ; that trees "need to produce energy and when they photosynthesise they produce like energy"and that food is "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 conflict between how she understood the role of energy in biology, and what she was taught in physics.

However, on further questioning, she seemed able to recast her biology knowledge to fit what she had been taught in physics:

So in physics, they tell you (that) you cannot make or destroy energy.

Yeah.

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

(No response – Pause of c.2 seconds)

But only in biology, not in physics?

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

So in an interview context, once the linkage was explicitly pointed out, Amy seemed to recognise that the principle learnt in physics should be applied in biology. However, she did not spontaneously make this link, without which the nature of respiration was misunderstood (in terms of energy being created from matter). This would appear to be an example of a fragmentation learning impediment, as although Amy had learnt about the conservation of energy she did not immediately how this related to what she had studied in biology, about respiration.

Converting glucose and oxygen into energy

Keith S. Taber

Amy was a participant in the Understanding Science Project. Amy was a Y10 (14-15 year old) student who had separate lessons in biology, chemistry and physics. When I spoke to her, she told me that in biology she was studying respiration which she suggested was "converting glucose and oxygen into energy…through anaerobic respiration and aerobic respiration". This 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 recognised that energy was an idea which appeared in both topics:

The work in physics on electricity and the work in biology on respiration, is there any connection there?

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 again, 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 broken down and converted into energy".

It is a basic principle in science, that energy cannot be created or destroyed. (Since Einstein, is has become clear that strictly matter can be considered as if a form of energy, and interconversion can take place, for example in nuclear processes, but this effect is negligible in normal chemical systems.) What Amy took away from her biology classes, though, was that energy could be produced in respiration and photosynthesis, and that indeed glucose and energy were converted into energy in respiration (i.e., an alternative conception). Amy did not seem to be applying the principle of energy conservation here – although it transpired (see here) that she had recently studied this in her physics lessons.

Carbon electrons will be bigger than chlorine electrons

Carbon electrons will have more mass and charge than chlorine electrons

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). She was shown a representation of a tetrachlomethane molecule.

Understanding Chemical Bonding project – Focal figure 3

When Annie was asked about the diagram, she was not sure if the differently represented electrons would actually be different from each other, She suggested that perhaps electrons from different atoms would actually contain some of the particular element. Annie seemed unsure where one could tell the difference between electrons from different atoms, but her intuition seemed to tell her they should be different,

Under further questioning, Annie was able to suggests ways in which carbon electrons would be different from chlorine electrons. Most science teachers may expect it would be quite obvious that one electron is much like another one in terms of essential properties (e.g., charge, rest mass). We probably assume students will readily appreciate this, and perhaps that it is not a point that needs to be emphasised. We might expect a student would immediately reject any suggestion that electrons from different atoms should be fundamentally different.

Do you think they would be the same size, electrons from carbon and electrons from chlorine?

No.

Which ones will be bigger, do you think?

The carbon ones.

Do you think they're the same charge? The same electrical charge?

No.

(pause, c.5)

No, which one do you think will have a bigger charge?

(pause, c.2s)

The carbon.

Yeah, what about colour. What colour do you think they will be?

Colours. What of the actual electrons?

Mm.

Mm, (pause, c.5s) I don't think they'd really have a colour, but I think if they had to have a colour, then they'd pick out the colour from the element.

A teacher is likely to expect an A level student to appreciate that all electrons are intrinsically the same. Annie seemed to think that the electrons of different atoms were different, somehow reflecting the particular element, and open to the idea they may differ in mass and charge, and possibly even colour.

Whilst Annie's comments are at odds with canonical science, they reflect thinking that is quite common among learners who often fail to appreciate the core principle of sub-microscopic models of matter, i.e., that the emergent properties of matter at macroscopic scale are explained in terms of the different properties of the tiny particles (i.e., quanticles) from which matter is conjectured to be constituted at a much finer scale. She was not keeping clearly distinguished macroscopic properties (such as colour) and properties that sub-atomic particles could have.

Electrons would contain some of the element

Electrons from different elements would be different – perhaps because they would actually contain some of the element in the electron?

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). She was shown a representation of a tetrachlomethane molecule.

Understanding Chemical Bonding project – Focal figure 3

When Annie was asked about the diagram, she noted that (following a representational convention) the electrons were represented differently. Using different symbols like this is quite common, but is little more that a bookmaking tool – to help keep count of the number of electrons in the molecule in relation to those that would be present in discrete atoms.

…are there any bonds [shown] in that diagram do you think?

Yes.

How many?

Four.

Four bonds, so we've got four bonds there. Erm, are the bonds actually shown?

Yeah.

So how are they represented on the diagram?

By the circles that overlap, and they're showing it by the electrons, the outer-shell electrons in the chlorine have got black dots and the ones from carbon have got just circles.

Okay. So the carbon electrons and the chlorine electrons are signified in a different way

Yeah.

I followed up this point to check Annie understood that the convention did not imply that there was any inherent difference between the electrons.

So what would be the difference between a carbon electron and a chlorine electron?

(pause, c.5s)

The expected answer here was 'no difference', but the pause suggested Annie was not clear about this. So I set up an imaginary scenario, a kind of thought experiment:

If I gave you a bottle of electrons – which I can't do – how would you be able to tell chlorine electrons from carbon electrons – in what ways would they be different?

They would be different because, erm, I don't know if they would actually contain some of the element in the electron.

Do you think they might have little labels on some with "C"s and some with "Cl"s or

Yeah, I don't know if you got an electron, and you could sort of if you took one single one you could say, right that's chlorine and that one's carbon.

You are not sure, you are not sure if you could, or not?

No.

The idea that an electron might contain some of the element seems to miss the key idea that macroscopic phenomena (samples of element) are considerer to energy from extensive ensembles of submicroscopic particles ('quanticles').

Annie did not seem too sure here – perhaps her intuition was that a carbon electron would be different to a chlorine electron, but she could not suggest how. Electrons have no memories, and there is no way of knowing whether an electron has previously been part of a particular atom (or ion or molecule). A free electron is not meaningfully a chlorine electron or a carbon electron. However, students do not always appreciate this, and may consider that free electrons in some sense belong to an atoms they they derived form, and even that this may later have consequences (as with the 'history' conjecture in thinking about ionic bonding).

Annie went on to suggest that carbon electrons would be bigger than chlorine electrons.

Peter and Patricia Pigeon set up house together

Keith S. Taber

In my work I've spent a lot of time analysing the things learners say about science topics in order to characterise their thinking. Although this work is meant to have an ethnographic feel, and to be ideographic (valuing the thinking of the individual in its own terms), there is always an underlying normative aspect: that is, inevitably there is a question of how well learners' conceptualisations match target curricular knowledge and canonical science. We all have intuitions which are at odd with scientific accounts of the world, and we all develop alternative conceptions – notions which are inconsistent with canonical concepts.

Peter and Patricia started seeing each other at this local fence earlier this year.

Soon passion got too much for them and they (publicly) consummated their relationship on this very fence (some birds have no shame).

It is easier to spot this in others (you think what?!) than it is in ourselves. But occasionally you may reflect on the way you think about a topic and recognise aberrations in your own thinking. One of these examples in my own thinking relates to bird's nests. I know that birds build nests as a place to lay and hatch eggs. Using the ground would be very dangerous due to vulnerability to predators. Simply using branches would be precarious – especially as eggs are hardly best shaped to be balanced on a tree branch. I also know that once the young are fledged have fled the nest, it has outlived its purposes.

They quite liked the area, and decided to look for a place nearby.

Soon they had identified a nice place to build their new home in some nearby ivy.

Yet it was only a few years ago – I think when came across discarded nests in the garden – that I released I have carried around with me since quite young the metaphor that a nest is a bird's home – it is where the bird family lives. Perhaps I made up that idea as a child. More likely I was told that or heard it on a children's programme. If so, perhaps it was not meant to be taken too literally – it was just meant to compare the nest with something that would be familiar to a child. But I think well into adulthood I had this notion of that birds lived in trees – not explicitly, but insidiously in the back of my mind: as if a bird had a home in a tree and that was where it was based – unless and until perhaps it could afford to move upmarket to a better tree!

They decided to do their own build, which involved Peter in the tiring work of going out to get building materials.

Peter set about the serious business of setting up their new dream home.

Peter was quite confident, and would often return which rather large pieces of nesting material.

"Oh, that seems to have got caught up."

Over time Peter started to be more realistic in selecting material he could get through the front door.

Although I was well aware (at one level) that birds do not have permanent family homes to which they return at the end of a hard day's exertions, I also had this nest=home identity at the 'back of my mind' giving the impression that this is how birds live. As humans we take for granted certain kinds of forms of life (perhaps home, work, family, etc.), and these act as default templates for understanding the world. This makes anthropomorphising nature seem quite a natural thing to do.

Peter heading out to work, again.

And getting home with his latest acquisition – landing on his feet.

Watching this process develop was quite entertaining. Peter would spend ages pecking at pieces of plant that were firmly fixed in the ground, ignoring nearby loose material. His early attempts to take material back to the nest were troubled. He would take material that was too large to get through the foliage into the secluded nesting area. He would also fly close to 'home' and then abort as found he could not land with his goods. However, he soon seemed to learn what worked, and developed a technique of first flying onto the fence or the roof the ivy was growing on to, so he would not be flying up to the nesting place from the ground in a single stage.

The sequences below show the pigeon flying out from, and back to, the nest.

The jumping/diving action is clear in the sequence below:

The fourth and fifth frames in the sequence below show the 'landing gear' coming into position (reminiscent of a bird of prey taking its prey):

The landing action is also clear near the end of the sequence below:

Another take off. catching the first few flaps:

My favourite sequence – quite extended for my hand-held camera work! – in the 11th frame our pigeon is just entering frame right. But notice a sparrow sitting on top of the foliage to the left. The sparrow has presumably seen/heard the much larger bird comings it way, and in the next frame can be seen to be moving its wings ready to take off. The next three frames have the sparrow heading right as the pigeon moves to the left (the sparrow is a smudge beneath the pigeon's left wing in the third of these frames), and the sparrow appears to have disappeared from view in the next, but must have been obscured by the pigeon as it seen to the right of the next frame. The sequence ends with the pigeon in landing mode.

Electrons repel each other, keeping them out of the nucleus

Keith S. Taber

Brian was a participant in the Understanding Chemical Bonding project. He was interviewed during the first year of his college 'A level' course (equivalent to Y12 of the English school system). Brian 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. He was shown a simple representation of an atom which he identified as showing "electron configuration…of an element, sodium".

Focal figure shown to Brian

Brian identified the electrons and nucleus, and was asked about the arrangement of the electrons:

Can you tell me why the electrons stay there, in these positions, why they don't fly off into space?

'Cause they're held by the nucleus.

In what way does the nucleus hold them, any idea?

It's got a positive charge, and so attracts the electrons, which are negatively charged.

Okay, so, it's got an electrical attraction there.

Yeah.

Why don't they just go into the nucleus then, if they're attracted, why don't they just get pulled into the nucleus?

Because, 'cause there's more than one electron, they repel each other, and keep them out.

Ah, so what about these ones [on opposite sides of the nucleus] though, these repel each other do they, even though they

Yeah.

are drawn on opposite sides?

Yeah.

So that's what stops them actually falling into the nucleus, that they repel each other?

Yeah.

It seems that Brian recognised electrical interaction between the nucleus and the electrons in an atomic structure. He also recognised that electrons would repel each other, but did not seem to have considered that in itself that was an insufficient explanation for the structure of the atom (as, for example, the sole electron in a hydrogen atom does not fall into the nucleus).

Although Brian's explanation was based on sound principles (negative electrons repel each other), it is an alternative conception. Coulombic forces are proportional to charges and diminish with separation – inspection of the figure should suggest that the two inner electrons (tending to be pushed inwards by outer electrons) at least must experience net force towards the nucleus.

The stability of atoms – the failure of electrons to spiral into the nucleus leading to atoms collapsing – was one of the phenomena which led to the development of quantum theory. In classical physics the stability of electron orbits was a puzzle to be solved, as orbiting electrons 'should' have acted as electrical oscillators, and emitted energy as their orbits decayed into the nucleus whilst the atom (very quickly) collapsed. Quantum theory posited limited allowed energy states, rather than a continuum of possibilities – but learners new to the topic do not know about this.

Often learners simply accept atomic structure when presented with planetary-system type representations of the atom. 'Quanticles' such as atoms are so far from direct human experience that they presumably seem strange enough such that questions that might seem obvious to a teacher do not arise for students. (Students also commonly accept the 'atom is like a tiny solar system' teaching analogy, and may map inappropriately between the two systems.)

A salt grain is a particle (but with more particles inside it)

Keith S. Taber

Sandra was a participant in the Understanding Science Project. When I interviewed Sandra about her science lessons in Y7 she told me "I've done changing state, burning, and we're doing electricity at the moment". She talked about burning as being a chemical change, and when asked for another example told me dissolving was a chemical change, as when salt was dissolved it was not possible to turn it back to give salt grains of the same size. She talk me that is the water was boiled off from salt solution "you'd have the same [amount of salt], but there would just be more particles, but they'd be smaller".

As Sandra had referred to had referred to the salt 'particles' being smaller,(as as she had told me she had been studying 'changing state') I wondered if she had bee taught about the particle model of matter

So the salt's got particles. The salt comes as particles, does it?
Yeah.
Do other things come as particles?
Everything has particles in it.
Everything has particles?
Yeah.
But with salt, you can get larger particles, or smaller particles?
Well, most things. Like it will have like thousands and thousands of particles inside it.
So these are other types of particles, are they?
Mm.

So although Sandra had referred to the smaller salt grains as being "smaller particles", it seemed he was aware that 'particles' could also refer to something other than the visible grains. Everything had particles in. Although salt particles (grains?) could be different sizes, it (any salt grain?) would have a great number ("like thousands and thousands") of particles (not grains – quanticles perhaps) inside it. So it seemed Sandra was aware of the possible ambiguity here, that there were small 'particles' of some materials, but all materials (or, at least, "most things") were made up of a great many 'particles' that were very much smaller.

So if you look at the salt, you can see there's tiny little grains?
Yeah.
But that's not particles then?
Well it sort of is, but you've got more particles inside that.

"It sort of is" could be taken to mean that the grains are 'a kind of particle' in a sense, but clearly not the type of particles that were inside everything. She seemed to appreciate that these were two different types of particle. However, Sandra was not entirely clear about that:

So there's two types are of particles, are there?
I don't know.
Particles within particles?
Yeah.
Something like that, is it?
Yeah.
But everything's got particles has it, even if you can't see them?
Yeah.
So if you dissolved your salt in water, would the water have particles?
Ye:ah.
'cause I've seen water, and I've never seen any particles in the water.
The part¬, you can't actually see particles.
Why not?
Because they're too small.
Things can be too small to see?
Yeah.
Oh amazing. So what can you see when you look at water, then? 'cause you see something, don't you?
You can see – what the particles make up.
Ah, I see, but not the individual particles?
No.

Sandra's understanding here seems quite strong – the particles that are inside everything (quanticles) were too small to be seen, and we could only see "what the particles make up". That is, she, to some extent at least, appreciated the emergence of new properties when very large numbers of particles that were individually too small to see were collected together.

Despite this, Sandra's learning was clearly not helped by the associations of the word 'particle'. Sandra may have been taught about submicroscopic particles outside of direct experience, but she already thought of small visible objects like salt grains as 'particles'. This seems to be quite common – science borrows a familiar term, particle, and uses it to label something unfamiliar.

We can see this as extending the usual everyday range of meaning of 'particle' to also include much smaller examples that cannot be perceived, or perhaps as a scientific metaphor – that quanticles are called particles because they are in some ways like the grains and specks that we usually think of as being very small particles. Either way, the choice of a term with an existing meaning to label something that is in some ways quite similar (small bits of matter) but in other ways very different ('particles' without definite sizes/volumes or actual edges/surfaces) can confuse students. It can act as an associative learning impediment if students transfer the properties of familiar particles to the submicroscopic entities of 'particle' theory.

Dissolving salt is a chemical change as you cannot turn it back

Dissolving salt is a chemical change as you cannot turn it back as it was before

Keith S. Taber

Sandra was a participant in the Understanding Science Project. When I interviewed Sandra about her science lessons in Y7 she told me "I've done changing state, burning, and we're doing electricity at the moment". I asked her about burning:

Well, tell me a bit about burning then. What's burning then?
It's just when something gets set on fire, and turns into ash, or – has a chemical change, whatever.
Has a chemical change: what's a chemical change?
It means something has changed into something else and you can't turn it back.
Oh I see. So burning would be an example of that.
Yeah.

So far this seemed to fit 'target knowledge'. However, Sandra suggested that dissolving would also be a chemical change. Dissolving is not normally considered a chemical change in school science, but a physical change, the distinction is a questionable teaching model. (Chemical change is said to involve bond breaking/making, and of course dissolving a salt does involve breaking up the ionic bonding to form solvent-solute interactions.)

Are there other examples?
Erm – dissolving.
So give me an example of something you might dissolve?
Salt.
Okay, and if you dissolve salt, you can't get it back?
Not really, not as it was before.
No. Can you get it back at all?
Sort of, you can like, erm, make the, boil the water so it turns into gas, and then you have salt, salt, salt on the, left there. Sometimes.
But you think that might not be quite the same as it was before?
No.
No. Different in some way?
Yeah
How might it be different?
Be much smaller.
Oh I see, so do you think you'd have less salt than you started with?
You'd have the same, but there would just be more particles, but they'd be smaller.
Ah, so instead of having quite large grains you might have lots of small grains
Yeah.

So Sandra was clear that one could dissolve salt, and then reclaim the same amount of salt by removing the solvent (water) which from the canonical perspective would mean the change was reversible – a criterion of a physical change.

Yet Sandra also thought that although the amount of salt would be conserved, the salt would be in a different form – it would have different grain size. (Indeed, if the water was boiled off, rather than left to evaporate, it might indeed be produced as very small crystals.)

So, Sandra seemed to have a fairly good understanding of the process, but because of the way she interpreted the criterion of a chemical change, something [salt] has changed into something else [solution] and you can't turn it back [with the same granularity]. Large grains will have changed into small grains – so this would, to Sandra's mind, be a chemical change.

Science teachers deserve a great deal of public appreciation. A teacher can teach something so that a student learns it well – and yet still form an alternative conception – here because of the inherent ambiguity in the ways language is used and understood. Sandra's interpretation – if you start off with large particles and end up with smaller particles then you have not turned it back – was a reasonable interpretation of what she had learnt. (It also transpired there was ambiguity in quite what was meant by particles.)

Puppies that automatically retrieve your stick

Dogs that have been taught over and over to retrieve have puppies that automatically have already got that sense 

Keith S. Taber

Bert was a participant in the Understanding Science Project. In Y11 he reported that he had been studying about the environment in biology, and done some work on adaptation. he gave a number of examples of how animals were adapted to their environment. When asked to explain how this occurred he initially used an example of selective breeding in dogs.

our homework we did about adapting, like how polar bears adapt to their environments, and camels….

And so a polar bear has adapted to the environment?

Yeah.

So how has a polar bear adapted to the environment?

Erm things like it has white fur for camouflage so the prey don't see it coming up. Large feet to spread out its weight when it's going over like ice. Yeah, thick fur to keep the body heat insulated.

What about a camel then?

Well it has long eyelashes to keep the sand out of it. It has pretty much all its fat stored in its hump so that it can erm, so all the body, so that not much body heat is produced from everywhere else. It doesn't have hair on its belly to increase heat loss. And yeah, oh yeah, they're quite big so it has quite a lot of grip on the sand.

No, okay. So do you have any other examples of adaption?…

Oh well, well there's humans isn't there. Because like they started off like with an arched back and they went on all-fours and everything. And well their minds obviously have adapted and evolved, yeah. Erm (pause) and dogs, they have different … because people who are actually breeders, they, when they breed dogs they breed them to be like, like Retrievers. Because they've like been taught over and over to retrieve. And so when they have puppies then they automatically have already got that sense. That's not really adapting though is it?

So somebody has trained these dogs to go and, when they shoot birds or something, they're trained to go and get the birds they've shot and bring them back?

Yes.

Okay. And if you do that enough, baby puppies bred from those dogs will just know to do that?

Well they won't know to do that, but they'll already have that kind of sense. And like, well my dog that I have, it's a Chocolate Labrador, and I said look, she had webbed feet which is adapted for swimming, for retrieving, I don't know, retrieving birds from water or something.

Although Bert was aware of how traits could be passed on to offspring he was thinking in terms of the inheritance of acquired characteristics – a Lamarkian model of evolution – rather than the selection of qualities that vary across a population. For some pupils the notion of evolution makes sense, but in terms of changes that occur in an individual in response to environmental challenges being somehow passed on to their offspring. The inheritance of acquired characteristics is a scientific concept, that is a historical (scientific) concept, but not a canonical (current scientific) concept, so Bert's understanding of evolution would be considered an alternative conception.

(Bert then went on to consider an example of a naturally occurring adaptation, the polar bear's fur, however he again considered this in terms of an acquired characteristic being passed on to future generations.)

Memories from a pandemic

Memories from a pandemic: On recollection, confabulation, and verisimilitude!

Keith S. Taber

I had gone into the office to collect something. (My office is in the Science Education Centre of the University's Faculty of Education, located on the site of Homerton College Cambridge.) Due to the global pandemic, and government advice (and later instructions) the office had been in lock down for some time. I'd been away for so long that aspects of the room seemed unfamiliar! The room was something of an oblong, at the back of the building near the technician's area. It was rather cluttered: that was certainly familiar, but it struck me, having been away for some weeks, just how cluttered.

I was pretty sure I needed to collect a lead, but could not see the lead I wanted. I noticed some leads with very thick insulation connecting to the computer – were these SCART leads: I did not remember these being used in the office. But that was not what I was looking for.

I've been in this office quite a few years (well over a decade now) and whilst looking around I found some things I had rather forgotten about. There were some small toy cars – of the kind that that were used on some gravity powered racing tracks when I was a child. These were approx. 1:64 scale, and made to roughly replicate real models, and painted in various colours. It might seem an odd thing to have in an adult's (there may be an unjustified assumption there?) office, but for my first decade in the University I had largely worked in teacher education and led on the physics teaching component – so that provided a good excuse for having lots of different toys!

Another thing that was initially unfamiliar was a large card. This was about A3 size, or originally A2 but folded like a greetings card. Inside were various other post-card sized cards attached, as well as some confectionery wrappers! What was this? It was coming back to me. One year I'd sent a message out to all the students who had finished the course (this was presumably our one-year Educational Research course), and many had replied from all over the world, and I'd made this as a record. Had I sent them all chocolate, and they had returned the wrapper with a greeting? Or had they sent that the confectionery to me from different locations? I was not sure now – the details were bit hazy.

Coming back into the office, and indeed into Cambridge from the satellite town where I live, for the first time in a while was a little odd. I could see into the school next door to our site. There were not many children (most were now at home, with just key workers' children and vulnerable children being in school to be looked after) but those there seemed to be playing happily (both outside and inside classrooms – I could not see anyone supervising) and unperturbed by the current emergency. This seemed reassuring, if a little odd.

I could also see into a classroom of an adjacent college (not a college of the university, but one of the many independent sixth form colleges that allow, mostly overseas, students to study at Cambridge at university entrance level). There were a few young people visible studying. A teenage boy and girl were sitting next to each other working on something together. They were even touching I noticed – nothing inappropriate in normal times – but these are not normal times.

I'd been to the College Combination Room (a staff room for all those working in Homerton – whether academics, clerical, gardeners, or whatever). It was almost empty. I had a conversation there with a colleague I recognised. I think I had wanted to say something about the prime minister being in hospital, along the lines that if he were to die from COVID-19 that would be a terrible loss to his family and friends, but might do wonders for getting across the government's message about social distancing – his one death could save hundreds. But although this was a thought experiment along the lines of those 'trolley' dilemmas used to explore ethical reasoning, I thought it might come across as a little callous. (It is one thing to conjecture scenarios involving the deaths of unnamed imaginary people, but not a real, ill, human being.) [Since publishing this, I have learned this evening on the BBC Radio News that Mr Johnson's health has deteriorated, and he has been placed in intensive care. I do, of course, wish him well along with others suffering from the disease.]

I saw it was 14.00 (2 p.m.) and felt I should have gone to the main faculty building to take a class (although there are no classes now, so just force of habit there I suppose). I wanted to get a cup of coffee to take with me to the class (force of habit, again?), but I saw the coffee machine, and all the tea making paraphernalia, were gone. I assumed that this was because of the current emergency – having a place where people can come to get tea and coffee would encourage the social mixing that we need to avoid. The College must have taken all the refreshments away.

On leaving the Combination room I moved into a corridor (known as Pauper's Walk) but, as I entered the corridor, I saw another colleague enter from the far end. Current protocols suggested to me that I needed to stand back against the wall, and allow her to pass on the other side. However, she had not seen me for a while, and seemed to want to come up to me to talk.

Back in my office, I noticed that some things had been moved since I had been in regularly (pre-pandemic). Some filing cabinets had been shoved out of position, apparently to get access to some large cupboards built into the walls. I did know what was in those cupboards – actually I am not sure I had ever noticed them before. I assumed the technicians used them for storage and had been in to get something, and had needed to shift the cabinets across the floor.

I also noticed that the builders (who had been on site an interminable time, working on one project after another) had made a small hole in the floor in the corner of the room. Through that I was able to see the large, and very 'modern' looking, installation beneath the floor of the store room – presumably the new power plant to heat the building. I could see it was subject to a continuous, and quite extensive, waterfall. I wondered if this was necessary. If the building is closed at the moment, was this not wasting a good deal of water? Or, I wondered, was it a safety precaution that the core needed to be kept cooled even though we were not meant to be operating at the moment?

I had given up on finding the lead I was looking for, and decided I should head for home. I felt a little uneasy about this. The restrictions were still in place. If I was stopped by a police officer, could I really justify my going to work as essential if my main justification had been to look for a lead that I could manage to work at home perfectly well without? I was also uneasy about getting the bus back from the centre of Cambridge to my home – did I really want to be using public transport at this time?

It was then that I started to experience what might be considered cognitive dissonance. Why had I not been concerned about getting the bus into Cambridge? Actually, I did not recall having got the bus into work. The only other viable way I could have got there was cycling, which given the distance, my fitness, and my cargo trike, was, although certainly possible, not an undertaking I would likely have made and immediately forgotten. It was at this point that I released that I did not remember going into work because I had not done so. It was a dream, and, realising that, I woke up at home.

But it was a dream like so many of my dreams – experienced as real, and involving a lot of remembering of things that never happened. (I do not mean remembering the dream when awake, but the experience of remembering in the dream). There is an independent college just adjacent to our building where I often see students studying as I pass by. But no school. The combination room was a real (or at least realistic) memory, as was the colleague I talked to there and the corridor outside – but the other colleague who approached me in the corridor (although seen with clarity in my dream) was not someone I know, or as far as I know based on any real person.

The office I was in (in my dream) was not actually my office, or any office we have in the building (much more like an office I shared at the Institute of Education in London for a year when a visiting fellow there), and was in a different part of the building to my real office.

There is no power plant built under our store room (though last Summer something like this, sans waterfall, was built under the Homerton College lawn). I had left my laptop power lead in the office when I brought the laptop home, and I had considered whether I should go back for it (before we were officially banned from the University buildings) and see if there was anything else I needed before the lock-down: but had decided it was not necessary or a good use of time, or sensible in the circumstances. (But why could I not find the right lead in the dream?)

I have various things in the office from my days working on the PGCE teacher preparation course (a magnetic pendulum for example), but I am not sure if there are toy cars (perhaps there are, and I have forgotten them in my waking life). The large card displaying messages (and chocolate wrappings) from various students has no real counterpoint, but could perhaps be seen as a composite of various post cards and gifts I've been given or sent by students over the years.

The Dream of Human Life
After Michelangelo
The National Gallery
The Dream of Human Life
After Michelangelo (From The National Gallery)

Why bother writing about a dream at such length? Because it made me think about memory. In the dream I experienced things that are real, some that were realistic enough (the non-existent colleague in the corridor seemed as real as the real one in the Combination Room) and some that seem (now) fantastic distortions or syntheses of past experiences.

But what was most notable, to my mind, is the role of memory in the dream. When I found the cars, and the card, I was initially nonplussed, but then remembered them from years before (even though, in the case of the card at least, I could not have actually remembered something that never existed). When there was no coffee available in the Combination Room I remembered the current restrictions and inferred this was a precaution the College had taken.

When I found the hole in the floor of my office, I remembered that the builders have been excavating and installing equipment beneath the store room next door (they had not, and the store room was not next door to my actual office). However, a shiny new futuristic apparatus as part of the heating system had recently been open to incidental passer-by inspection as part of ongoing (and indeed interminable) works elsewhere on site – perhaps conflated in my dream with the ground source heat pump under the lawn. In my dream I recognised and remembered things that were real, imagined but possible, and fantastic (the waterfall installed in the excavated cave under our store room, even if not exactly where "the sacred river, ran, through caverns measureless to man"), with equal verisimilitude, as seeming equally likely and trustworthy. The imaginary colleague was as real to me as the remembered real one.

I had no doubts during my dream that I had been in my office, even if it seemed a lot narrower than I recalled. I did not remember having toy cars there, but immediately saw why they might have been useful in teaching. I was initially not at all sure what to make of the large card with the various additions attached inside – but then I 'remembered' (actually, constructed an account of) what I had done years before, and the responses this had initiated, and what I had then done to commemorate those response from past students. It seems a little odd that in my sleep I could 'remember' this unlikely object, but could not remember having gone into work (where there is much genuine experience on which to have constructed a recollection). Perhaps I was just reaching the point where I (my body) was ready to wake, and so my dream became lucid, initiating my awakening. (The thinking we do in dreaming seems worth the effort at the time, until we realise it is 'just' a dream.)

It is perhaps not surprising that in dreams we recognise, and even remember, things that are not real, things that are distorted, and things that are syntheses or different experiences, or that are actually post hoc justifications that enable us to make sense of otherwise confusing (dreamed) experiences. What struck me, though, was how this phenomenon – the way memory seems to cheat and fabricate during dreams – was actually no different from how research suggests memory works in our waking lives. When students tell me they have been taught something that I realise is incorrect in their science lessons, I am always aware they may be recalling correctly, but it is also quite possible that what they 'remember' being told was not what the teacher actually said at the time.

So we might readily dismiss as false things we thought we were remembering when dreaming. But we usually trust a memory we have when we are awake, although research has shown that the things we remember clearly in our waking lives can also be distortions – or even confabulations – as our mind guesses and fills-in what we infer must have happened in order to to make sense of current experience.

A sobering, perhaps even arousing, thought.

A chemical bond would have to be made of atoms

Keith S. Taber

Amy was a participant in the Understanding Science Project. When I had talked to Amy when she was in Y10 she had referred to things being bonded: "where one thing is joined on to another thing, and it can be chemically bonded" and how "in a compound, where two or more elements are joined together, that's an example of chemical bonding".

The following year, in Y11, 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."

Source: Image by WikimediaImages from Pixabay

As Amy had told me "everything is made up 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".

Not only is this an alternative conception, but to a chemist, or science teacher, the idea that chemical bonds are themselves made up of atoms seems incongruous and offers a potential for infinite regress (are those atoms in the bonds, themselves bonded? If so, are those bonds also made of atoms?)

This alternative conception could be considered a kind of associative learning impediment – that is where a learner makes an unintended link and so applies an idea outside of its range of application. All material is considered to be made of atoms – or at least quanticles comprising one of more nuclei bound to electrons (i.e., ions, molecules). Even this is not an absolute: the material formed immediately after the big bang was not of this form, and nor is the matter in a neutron star, but the material we usually engage with is considered to be made of atom-like units (i.e., ions, molecules).

But to suggest that Amy has made an inappropriate association seems a little unfair. Had Amy thought "all matter was made of atoms" and then suggested that chemical bonding was made of atoms this would be inappropriate as chemical bonding is not material but a process – electrical interactions between quanticles. Yet it is hard to see how one can over-extend the range of 'everything', as in "everything is made up of atoms".

There is an inherent problem with the motto everything is made up of atoms. It is probably something that teachers commonly say, and think is entirely clear – that it is obvious what its scope is – but from the perspective of a student there is not the wealth of background knowledge to appreciate the implied limits on 'everything'.

Learners will readily pick up teaching mottos such as "everything is made of atoms" and take them quite literally: if everything is made of atoms then bonds must be made of atoms. So although she was wrong, I think Amy was just applying something she had learnt.