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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.

Why write about Cronbach's alpha?

Keith S. Taber

What is Cronbach's alpha?

It is a statistic that is commonly quoted by researchers when reporting the use of scales and questionnaires.

Why carry out a study of the use of this statistic?

I am primarily a qualitative researcher, so do not usually use statistics in my own work. However, I regularly came across references to alpha in manuscripts I was asked to review for journals, and in manuscripts submitted to the journal I was editing myself (i.e., Chemistry Education Research and Practice).

I did not really understand what alpha was, or what is was supposed to demonstrate, or what value was desirable – which made it difficult to evaluate that aspect of a manuscript which was citing the statistic. So, I thought I had better find out more about it.

So, what is Cronbach's alpha?

It is a statistic that tests for internal consistency in scales. It should only be applied to a scale intended to measure a unidimensional factor – something it is assumed can be treated a single underlying variable (perhaps 'confidence in physics learning', 'enjoyment of school science practicals', or 'attitude to genetic medicine').

If someone developed a set of questionnaire items intended to find out, say, how skeptical a person was regarding scientific claims in the news, and administered the items to a sample of people, then alpha would offer a measure of the similarity of the set of items in terms of the patterns of responses from that sample. As the items are meant to be measuring a single underlying factor, they should all elicit similar responses from any individual respondent. If they do, then alpha would approach 1 (its maximum value).

Does alpha not measure reliability?

Often, studies state that alpha is measuring reliability – as internal consistency is sometimes considered a kind of reliability. However, more often in research what we mean by reliability is that repeating the measurements later will give us (much) the same result – and alpha does not tell us about that kind of reliability.

I think there is a kind of metaphorical use of 'reliability' here. The technique derives from an approach used to test equivalence based on dividing the items in a scale into two subsets*, and seeing whether analysis of the two subsets gives comparable results – so one could see if the result from the 'second' measure reliably reproduced that from the 'first' (but of course the ordering of the two calculations is arbitrary, and the two subsets of items were actually administered at the same time as part of a single scale).

* In calculating alpha, all possible splits are taken into account.

Okay, so that's what alpha is – but, still, why carry out a study of the use of this statistic?

Once I understood what alpha was, I was able to see that many of the manuscripts I was reviewing did not seem to be using it appropriately. I got the impression that alpha was not well understood among researchers even though it was commonly used. I felt it would be useful to write a paper that both highlighted the issues and offered guidance on good practice in applying and reporting alpha.

In particular studies would often cite alpha for broad features like 'understanding of chemistry' where it seems obvious that we would not expect understanding of pH, understanding of resonance in benzene, understanding of oxidation numbers, and understanding of the mass spectrometer, to be the 'same' thing (or if they are, we could save a lot of time and effort by reducing exams to a single question!)

It was also common for studies using instruments with several different scales to not only quote alpha for each scale (which is appropriate), but to also give an overall alpha for the whole instrument even though it was intended to be multidimensional. So imagine a questionnaire which had a section on enjoyment of physics, another on self-confidence in genetics, and another on attitudes to science-fiction elements in popular television programmes: why would a researcher want to claim there was a high level of internal consistency across what are meant to be such distinct scales?

There was also incredible diversity in how different authors describe different values of alpha they might calculate – so the same value of alpha might be 'acceptable' in one study, 'fairly high' in another, and 'excellent' in a third (see figure 1).


Fig. 1 Qualitative descriptors used for values/ranges of values of Cronbach's alpha reported in papers in leading science education journals (The Use of Cronbach's Alpha When Developing and Reporting Research Instruments in Science Education)

Some authors also suggested that a high value of alpha for an instrument implied it was unidimensional – that all the items were measuring the same things – which is not the case.

But isn't it the number that matters: we want alpha to be as high as possible, and at least 0.7?

Yes, and no. And no, and no.

But the number matters?

Yes of course, but it needs to be interpreted for a reader: not just 'alpha was 0.73'.

But the critical value is 0.7, is that right?

No.

It seems extremely common for authors to assume that they need alpha to reach, or exceed, 0.7 for their scale to be acceptable. But that value seems to be completely arbitrary (and was not what Cronbach was suggesting).

Well, it's a convention, just as p<0.05 is commonly taken as a critical value.

But it is not just like that. Alpha is very sensitive to how many items are included in a scale. If there are only a few items, then a value of, say, 0.6 might well be sensibly judged acceptable. In any case it is nearly always possible to increase alpha by adding more items till you reach 0.7.

But only if the added items genuinely fit for the scale?

Sadly, no.

Adding a few items that are similar to each other, but not really fitting the scale, would usually increase alpha. So adding 'I like Manchester United', 'Manchester United are the best soccer team', and 'Manchester United are great' as items to be responded to in a scale about self-efficacy in science learning would likely increase alpha.

Are you sure: have you tried it?

Well, no. But, as I pointed out above, instruments often contain unrelated scales, and authors would sometimes calculate an overall alpha (the computer found to be greater than that of each of its component scales – at least that would be the implication if it were assumed that a larger alpha means a higher internal consistency without factoring how alpha tends to be larger the more items are included in the calculation.

But still, it is clear that the bigger alpha the better?

Up to a point.

But consider a scale with five items where everybody responds to each item in exactly the same way (not, that is, different people respond in the same way as each other, just whatever response a person gives to one item – e.g., 2 on a scale of 1-7 – they also give to the other items). So alpha should be 1, as high as it can get. But Cronbach would suggest you are wasting researcher and participant effort by having many items if they all elicit the same response. The point of scales having several items is that we assume no one item directly catches perfectly what we are trying to measure. Whether they do or not, there is no point in multiple items that are effectively equivalent.

Was it necessary to survey science education journals to make the point?

I did not originally think so.

My draft manuscript made the argument by drawing on some carefully selected examples of published papers in relation to the different issues I felt needed to be highlighted and discussed. I think the draft manuscript effectively made the point that there were papers getting published in good journals that quoted alpha but seemed to simply assume it demonstrated something (unexplained) to readers, and/or used alpha when their instrument was clearly not meant to be multidimensional, and/or took 0.7 as a definitive cut-off regardless of the number of items concerned, and/or quoted alpha values for overall instruments as well as for the distinct scales as if that added some evidence of instrument quality, or claimed a high value of alpha for an instrument demonstrated it was unidimensional.

So why did you then spend time reviewing examples across four journals over a whole year of publication?

Although I did not think this was necessary, when the paper was reviewed for publication a journal reviewer felt the paper was too anecdotal: that just because a few papers included weak practice, that may not have been especially significant. I think there was also a sense that a paper critiquing a research technique did not fit in the usual categories of study published in the journal, but a study with more empirical content (even if the data were published papers) better fitted the journal.

At that point I could have decided to try and get the paper published elsewhere, but Research in Science Education is a good journal and I wanted the paper in a good science education journal. This took extra work, but satisfied the journal.

I still think the paper would have made a contribution without the survey BUT the extra work did strengthen paper. In retrospect, I am happy that I responded to review comments in that way – as it did actually show just how frequency alpha is used in science education, and the wide variety of practice in reporting the statistic. Peer review is meant to help authors improve their work, and I think it did here.

Has the work had impact?

I think so, but…

The study has been getting a lot of citations, and it is always good to think someone notices a study, given the work it involves. Perhaps a lot of people have genuinely thought about their use of alpha as a result of reading the paper, and perhaps there are papers out their which do a better job of using and reporting alpha as a result of authors reading my study. (I would like to think so.)

However, I have also noticed that a lot of papers citing this study as an authority for using alpha in the reported research are still doing the very things I was criticising, and sometimes directly justifying poor practice by citing my study! These authors either had not actually read the study (but were just looking for something about alpha to cite) or perhaps did not fully appreciate the points made.

Oh well, I think it was Oscar Wilde who said there is only one thing in academic life worse than being miscited…

'Correcting' for plagiarism

Keith S. Taber

Dear Stephen

Thank you for your email message from 'Competent Proofreaders' about the services provided by SPRINGEREDIT (viewpublishers@gmail.com / scrutinyeditors@gmail.com).

I would be interested in learning a little more about exactly what your service entails. I am pretty clear what is involved in 'Proofreading' and 'translating'. But I see you also offer 'correcting for plagiarism'. I wonder if you could tell me a little more about what your service involves here – what I would get for my 40 USD/1000 words?

My understanding is that plagiarism is when an author uses the ideas of another scholar as if their own – without acknowledging the original source. This can be considered not only poor scholarship, but academic malpractice, so I certainly understand why I should be careful to avoid plagiarism in any work I submit for publication. I can therefore see why a service that could correct for plagiarism might be worth investing in, as this could protect scholarly reputation (or in extreme cases, academic employment!)

But I cannot immediately see how you could help me with this. If I asked you to proofread a draft paper, then I know what to expect and I can see that it is very likely that a thorough proofread could technically improve my text. What would you actually do, however, if I submitted a draft paper for 'correcting for plagiarism' – how would you identify any plagiarism (that I might myself not be aware of) and correct it? What exactly would I be paying for?

Best wishes

Keith

(Read more about plagiarism)

She'd never thought about whether ionic bonding is the same thing as chemical bonding

Keith S. Taber

Amy was a participant in the Understanding Science Project. When I talked to her near the start of her GCSE 'triple science' course in Y10 she told me that ionic bonding was "atoms which have either lost or gained electrons so they are either positively or negatively charged" and that chemical bonding was "like in a compound, where two or more elements are joined together", but she seemed unsure how the two concepts were related.

I followed up on Amy's use of the term 'compound' to explore how she understood the term:

How would you define a compound?

Erm Something which has erm two or more elements chemically bonded.

… So you give me an example of that, compound?

Erm, sodium oxide.

Sodium oxide, okay, so there are two or more elements chemically bonded in sodium oxide are there?

Uh hm

And what would those two or more elements be?

Sodium and oxygen.

Okay. Erm, so when we say sodium oxide is chemically bonded, what we are saying there is?

[pause, c 2s]

Erm – a sodium atom has been bonded with a oxygen atom to form erm a new substance.

So Amy's example of a compound was sodium oxide, which would normally be considered essentially an ionic compound, that is a compound with ionic bonding. So this gave me an opportunity to test out whether Amy saw the bonding in sodium chloride and sodium oxide as similar.


Okay, so that was chemical bonding,

Mm.

and that occurs with compounds?

Yeah.

And what did you say about ionic bonding?

Erm, it's the outer electrons they are transferred from one element to another.

Now what does that occur in? You gave me one example, didn't you?

Uh huh

Sodium chloride?

Yeah

Erm. Would sodium chloride be er an element?

[pause, c.2s]

Sodium chloride, no.

No?

It would be a compound.

You think that would be a compound?

Yeah.

And a compound is two or more elements joined together by chemical bonding?

Yeah.

So Amy had told me that sodium chloride, which had ionic bonding, was (like sodium oxide) a compound, and she had already told me that a compound comprised of "two or more elements chemically bonded", so it should be follow that sodium chloride (which had ionic bonding) had chemical bonding.

Do you think sodium chloride has chemical bonding?

Er – I think so

And it also has ionic bonding, or is that the same thing?

Erm,

[pause, c.2s]

I dunno, I've never thought about it that way, erm,

[pause c.3s]

I'm not sure, erm

[pause, c.2s]

I dunno, it might be.

Clearly, whatever Amy had been taught (and interviewing students reveals they often only recall partial and distorted versions of what was presented in class) she had learnt

  • (1) that ionic bonding was transfer of electrons (an alternative conception) as in the example of sodium transferring an electron to chlorine; and that
  • (2) a compounds was where two or more elements chemically bonded together, and an example was sodium oxide where the elements sodium and oxygen were chemical bonded.

Yet these two pieces of learning seemed to have been acquired as isolated ideas without any attempt to link them. Initially Amy seemed to feel ionic bonding and chemical bonding were quite separate concepts.

When taken through an argument that led to her telling me that sodium chloride, that she thought had ionic bonding, was a compound, which therefore had chemical bonding, there should have been a logical imperative to see that ionic bonding was chemical bonding (actually, a kind of chemical bonding – as the logic did not imply that chemical bonding was necessarily ionic bonding). Despite the implied syllogism:

  • sodium chloride has ionic bonding
  • sodium chloride is a compound
  • compounds have elements chemically bonded together
  • therefore ionic bonding …

Amy was unsure what to deduce, presumably because she had seen the two concepts of ionic bonding and chemical bonding as discrete notions and had had given no thought to a possible relationship between them. However explicit teaching had been on this point, it is very likely that the teacher had expected students to appreciate that ionic bonding was a type of chemical bonding – but Amy had not integrated these ideas into a connected conceptual structure (i.e., there was a learning bug that could be called a fragmentation learning impediment).

Ionic bonding – compared with chemical bonding

Keith S. Taber

Amy was a participant in the Understanding Science Project. The first time I talked to Amy, near the start of her GCSE 'triple science' course in Y10 she told me that "in normal chemistry (i.e., the chemistry part of 'double science', as opposed to the optional additional chemistry lesson as part of 'triple science' that Amy also attended) we're doing about ionic bondingwhich she understood in terms of "atoms which have either lost or gained electrons so they are either positively or negatively charged" because "in ionic bonding it's the electrons that are transferred".

When asked other examples of ionic bonding apart from sodium and chlorine Amy told me "That's the one I did".

To a teacher it seems inherently obvious that ionic bonding is type of bonding – in much the way that a snare drum is a kind of drum or a conscientious student is a type of student. However, this may not always be obvious to students (even the conscientious ones).

When I asked Amy about bonding she referred to things being chemically bonded, and when I asked if ionic bonding was the same as chemical bonding, she was not sure how these concepts were related:

So what exactly is bonding?

Erm, where er one thing is joined on to another thing, and it can be chemically bonded or, yeah {laughs}

So we can talk about chemical bonding?

Mm.

Are there other types of bonding then?

Erm, there must be, if there's chemical bonding, I'm not sure, erm

[pause, c.5s]

But we talk about chemical bonding,

Mm.

and we talk about ionic bonding. So is ionic bonding the same thing as chemical bonding or is there a difference?

Erm, in, well 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 – erm – ionic bonding it's the erm electrons that are transferred. [pause, c.2s] I think.

It seems Amy had been taught about chemical bonding and had learn about this as "a compound, where two or more elements are joined together", and she had been taught about ionic bonding and had learnt that this was where "the electrons are transferred".

Ionic bonding is not (and need not be associated with) electron transfer. It is not possible form talking to Amy to now exactly what her teacher told her – clearly she could have misunderstood or forgotten material form class. It is possible that it was made clear that ionic bonding was one type of chemical bonding, but Amy either missed that point or did not now recall it. It is also possible is was not made explicit but was assumed to be obvious (especially if ionic bonding had been presented as part of a sequence on chemical bonding. Sadly, what is obvious to teachers is not always obvious to learners, and indeed I've seen in my interviews that students are not always clear when one topic has finished and another has started. There is no sense here that I wish to criticise the teacher (who for all I know gave an exemplary presentation of the chemical bonding), but would simply suggest that when teaching one can never assume what should be obvious is obvious and that it is probably difficult to be too explicit about key ideas, or to reiterate them too often!

So at this point it seemed Amy only knew one example of ionic bonding, sodium chloride, and did not associate this with compounds which had chemical bonding. This could be considered a fragmentation learning impediment – a failure to make a link that was expected from the teaching. I went on to ask her for an example of a compound, and a she told me about sodium oxide I thought this was an opportunity to probe at the association between ionic boding and chemical bonding a little more.

Ionic bonding – where the electron's transferred to complete the outer shell

Keith S. Taber

Amy was a participant in the Understanding Science Project. The first time I talked to Amy, near the start of her GCSE 'triple science' course in Y10 she told me that "in normal chemistry (i.e., the chemistry part of 'double science', as opposed to the optional additional chemistry lesson as part of 'triple science' that Amy also attended) we're doing about ionic bondingwhich 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 yeah that completes its outer shell and makes the sodium positively charged and the chlorine negatively charged".

Amy told me that "in ionic bonding it's the electrons that are transferred, I think."

So Amy had acquired a common alternative conception, i.e. that ionic bonding involved electron transfer, and that this occurs to atoms to complete their electron shells.

Ionic bonding refers to the forces between ions that hold the structure of an ionic substance together, rather than a mechanism by which such ions might hypothetically be formed – yet often learners come away form learning about ionic bonding identifying it with a process of electron transfer between atoms instead of interactions between ions which can be used to explain the properties of ionic substances.

Moreover, the hypothetical electron transfer is a fiction. In the case of NaCl such an electron transfer between isolated Na and Cl atoms would be energetically unfavourable, even if reactants containing discrete atoms were available (which is unrealistic).

Whether students are taught that ionic bonding is electron transfer is a moot point, but often introductory teaching of the topic focuses not on the nature of the bonding, but on presenting a (flawed) teaching model of how the ions in the ionic structure could form by electron transfer between atoms. As this mechanism is non-viable, and so not an authentic scientific account, it may seem odd that teachers commonly offer it.

One explanation may simply be custom or tradition has made this an insidious alternative conception. Science teachers and textbooks have 'always' offered the image of electron transfer as representing ionic bonding. So, this is what new teachers had themselves been taught at school, is what they often see in textbooks, and so what they learn to teach.

Another possible explanation is in terms of what what is known as the atomic ontology. This is the idea that the starting pint for thinking about chemistry at the submicroscopic level is atoms. Atoms do not need to be explained (as if in nature matter always starts as atoms – which is not the case) and other entities such as ions and molecules do need to be explained in terms of atoms. So, the atomic ontology is a kind of misleading alternative conceptual framework for thinking about chemistry at the submicroscopic level.

Current only slows down at the resistor

Current only slows down at the resistor – by analogy with water flow 

Keith S. Taber

Students commonly think that resistance in a circuit has local effects, and in part that is because forming a mental model of what is going on in circuits is very difficult. Often models and analogies can be useful. However when an analogy is used in teaching there is also the potential for it to mislead.

Amy was a participant in the Understanding Science Project. Amy (when in Y10) told me she had been taught to use a water flow analogy for electric current. However, because her visualisation of what happens in water circuits was incorrect, she used the analogy to inform an alternative conception about circuits:

Do you have any kind of imagined sort of idea, any little mental models, about what (the flow of electricity round the circuit) might look like? Do you have a way of imagining that?

Erm, yeah, 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 a one point, erm, the water flow has to slow down, and that's meant to represent the resistance of something.

So, so if I had my water, er, tank and I had a series of pipes, they'd be water flowing through the pipes, and if I had a narrower pipe at one point, what happens then?

The water would have to slow down.

So would it slow down just as it goes through the narrow pipe, or would it slow down all the way round?

Erm – just through that part.

(Amy does not appreciate the implications of conservation of mass {that is, the continuity principle} here – at steady state there cannot be a greater mass flow at different points in the circuit).

And so how do you imagine that's got to do with resistance, how does that help you understand resistance?

…well resistance, it slows the current down, but then erm, once it passes a resistor or something it, the current is free to flow through the wire again

Analogies can be very useful teaching tools, but when using them it is important to check that the students already understand the features of the analogue that are meant to be helpful. It is also important to ensure that they understand which features are meant to be mapped onto the target system they are learning about, and which are not relevant.

Analogies are only useful when the learner has a good understand of the analogue. In this case, as Amy did not appreciate that the water flow throughout the system would be limited by the constriction, she could not use that as a useful analogy for why a resistor influences current flow at all points in a series circuit. This is an example of where a teaching model meant to support learning, which actually misleads the learner. That is, for Amy, with her flawed understanding of fluid flow, the teaching model acted as a pedagogic learning impediment – a type of grounded learning impediment.

The electrons come from batteries

Electrons flowing through circuits come from batteries 

Keith S. Taber

Bill was a participant in the Understanding Science Project. I was asking him about topics he had studied in science, and I asked about electricity:

…have you done any work on electricity?

Erm, yes, I've done a bit.

Do you remember any of that?

Er we had to use symbols to draw circuits, and then we got to make those circuits.

Ah, so you remember doing the symbols, and you remember making up the circuits?

Yeah.

That's good. So what exactly is electricity?

It's made up of electrons which, erm, flow through wires, and into light bulbs to light them up. And they come from batteries.

Electrons do?

Yeah.

So what are electrons?

Erm {pause, c.4s} really don't know.

Bill here demonstrates a common alternative conception that in a circuit the battery, or other power supply, provides the electrons that flow, rather than providing a the electric field which acts on the electrons already present in the conducting path (e.g., in the wires).

International Congress on Advanced Materials Sciences and Engineering

To the organising committee of the International Congress on Advanced Materials Sciences and Engineering

Keith S. Taber

Dear Eve

Thank you for your kind invitation to be an invited speaker at the International Congress on Advanced Materials Sciences and Engineering (AMSE-2020). It is an honour that such esteemed colleagues as Professors Hans Fecht, Yoon-Bong Hahn, and Subhash C. Singhal, would feel that I can offer something of value to your Congress.

I was very taken that the committee felt that my paper on 'Upper Secondary Students' Understanding of the Basic Physical Interactions in Analogous Atomic and Solar Systems' should be considered to make such 'valuable contributions'  that you would like me to speak at your session on 'Materials and Energy'. I am aware that traditionally in scholarly circles, personal speaker invitations of this kind are seen as prestigious and are very much welcomed by those looking to build up a résumé/curriculum vitae.

Of course, I am honoured to be invited as a speaker, and to know that my work on secondary students' understandings of atomic and solar systems is held in such high esteem by your committee. However, I was somewhat surprised that the committee (I assume all busy leading experts in areas of materials science) would even be aware of my work, and frankly I am not sure why this work would justify you inviting me to speak to a congress of materials scientists.

I am sure that AMSE-2020 is intended to be a serious academic conference designed to share experts' cutting-edge research among a specialist field (rather than, say, just generate income for the organisers by signing up anyone who can be sufficiently flattered by a personal invitation) and so your committee must be very careful and highly selective in issuing personal invitations to potential speakers. This would suggest that your committee can appreciate much better than I can why my work would be of sufficient interest to experts in advanced materials science and engineering for them to wish to hear about it first hand.

I imagine that your committee and delegates put a high premium on science education and care very much about the future supply of well qualified young people into science and engineering fields, and it is gratifying to know that they find time to take an interest in educational research. I do wonder, however, if those attending the congress really want to hear about how teenagers make sense of the forces at work within atoms and the solar system rather than about current developments in their own field. Therefore I feel I must decline your kind invitation

Best wishes

Keith

Dear Dr. Keith S. Taber,
Hope everything goes well with you.
International Congress on Advanced Materials Sciences and Engineering (AMSE-2020) will be held in Hilton Vienna Danube Waterfront, Austria on July 22-25, 2020.
On behalf of the Committee, We are writing this time in order not to miss your participation at this congress. Based on your valuable contributions to Upper Secondary Students' Understanding of the Basic Physical Interactions in Analogous Atomic and Solar Systems, we sincerely hope that you can be a speaker at Session 8: Materials and Energy in our congress. …

Read about 'Conferences and poor academic practice'

Gases in bottles try to escape; liquids try to take the shape

Keith S. Taber

Bill was a participant in the Understanding Science Project. Bill, a year 7 (Y7) student, told me that:

"Gases, they try and fill whole room, they don't, like liquids, they stay at the bottom of the container, but gases go fill, do everywhere and fill, try and fill the whole thing." 

When asked "Why do they try and do that?" he replied that "Erm, I'm not sure." I suggested some things that Bill might 'try' to do, and asked "so when the gas tries to fill the room, is it the same sort of thing, do we mean the same sort of thing by the word 'try'?" Bill appreciated the difference, and recanted the use of 'try':

"No, I think I phrased that wrong, I meant that it fills the whole area, 'cause it can expand."

However, it soon became clear that Bill's use of the term came easily, despite accepting that it was misleading:

Okay. So it's not, the gas does not come in and say, 'hm, I think I'll fill the whole room', and try and do it?

No, it just does it.

It just does it?

It tries to get out of everywhere, so if you put it in the bottle, it would be trying to get out.

And later:

…are there particles in other things?:

liquids, yeah there is particles in everything, but liquids the particles move quite a lot because, well they have, oh we did this this [in the most recent] lesson, erm, they have energy to move, so they try and move away, but their particles are quite close together.

What about the gases?

The gases, their particles try to stay as far away from each other as possible.

Why is that? Don't they like each other?

No, it's because they are trying to spread out into the whole room.

And later:

…and you said that liquids contain particles? Did you say they move, what did you say about the particles in liquids?

Er, they're quite, they're further apart, than the ones in erm solids, so they erm, they try and take the shape, they move away, but the volume of the water doesn't change. It just moves.

What about the particles in the gas?

The gas, they're really, they're far apart and they try and expand.

Bill had only learnt about particles recently in science, but seemed to have already developed a habitual way of talking about them with anthropomorphism: as if they were conscious agents that strived to fill rooms, escape bottles, and take up the shape of containers.

To some extent this is surely a lack of familiarity with objects that can have inherent motion without having an external cause (like a projectile) or internal purposes (like animals) and/or having a suitable language for talking about the world of molecular level particles ('quanticles'). Such habits may be harmless, but it is a concern if such habitual ways of talking and thinking later come to stand for more scientific descriptions and explanations of natural processes (what has been called strong anthropomorphism).

Bill's lack of a suitable language for talking about particle actions could act as a learning impediment (a deficiency learning impediment), impeding desired learning.