Science Education Research and Practice

For discussion of research in science eduction, and how it informs teaching practice.

(A place to discuss some of my writing and to invite an opportunity for feedback.)

The motivation of this post was two-fold:

Firstly, I have blogged occasionally, mostly on the themes of science and/or education and/or research (Science – Education – Research) but the format and application used does not give an opportunity for anyone to respond. The facility here allows comments by readers (if I attract any).

I have also been involved in ongoing discussion about the extent to which published research and scholarship in science education is accessed by teachers and informs their work. There are barriers to teachers accessing much of this work, but some (even in the good journals) is published without cost to readers. I am coming to end of a period of editorship at a free access journal (Chemistry Education Research and Practice) published by the Royal Society of Chemistry.

All material on the journal is currently free access. It has been suggested to me that because the journal publishes peer-reviewer research, and therefore articles are written to a high technical standard, the material may not be directly informing the work of classroom chemistry teachers, and is largely of interest to others undertaking research in chemistry education. We know some teachers (in university departments, but also in schools) do read the articles – but it is difficult to gauge the level of this. Some articles are mostly pushing forward research programmes that are still some way from being applicable in classrooms (research can take time, and there may be ‘false starts’), and these are largely of interest to researchers, but many articles do present results with implications for classroom practice.

Research articles do have to be written in a formal way, citing other research, carefully detailing methods used, offering results in full, etc., but as a former school teacher myself, I think that teachers are perfectly capable of accessing and being informed by many research journal articles. Often these days teachers are introduced to educational enquiry in their preparation for professional practice, but even if not it is easy to find support in understanding educational research methods on the web.

I feel that a research journal could well be supported by an accessible blog, perhaps with a posting for each new article published that briefly introduces the paper, and invites readers to comment and perhaps discuss. Researchers might raise issues relating to their particular concerns; and teachers could focus on the value of the ideas in the classroom – how might the article inform their work and how did they get on if they tried to adopt any of the suggestions or perspectives in their own classroom.

Anyway, my second motivation was to look for a ‘proof of concept’. This blog does not belong to a particular journal, but I thought I would try the idea out with some of my own writing, and see if such post would attract any attention, and generate any dialogue. As an academic it is fairly easy to know if you are reaching other academics (e.g., there are tools such as Google Scholar that notify citations to authors), but in an area of scholarship such as Education researchers should also be looking to inform teachers. It is possible to write accounts of work for periodicals aimed at teachers (e.g. School Science Review, Education in Chemistry), as well as in journals, but even then there may be very limited feedback on what teachers make of the work.

So this is my proof (or not) of concept. If, after a while, I  find there are no pertinent comments/responses to my posts, I will have my answer.

Keith S. Taber

(Professor of Science Education, University of Cambridge)

With every mistake we must surely be learning – (George Harrison)

Daytime new moon.jpg

A study to explore the potential of designing teaching activities to scaffold learning: understanding circular motion

cover Effective Teaching and Learning

Taber, K. S., & Brock, R. (2018). A study to explore the potential of designing teaching activities to scaffold learning: understanding circular motion. In M. Abend (Ed.), Effective Teaching and Learning: Perspectives, strategies and implementation (pp. 45-85). New York: Nova Science Publishers.

This is one of two chapters (see the previous blog) in this book considering the theme of scaffolding.


Scaffolding tools?

The idea of scaffolding is often use in discussing how teaching supports learning. However, scaffolding has some rather specific requirements: it must allow a learner to achieve something they could not yet achieve unaided, but in a way that supports their development towards a level of mastery that does not require support. Sounds simple!

Support that simply makes something that is already within a learners’ competence easier is not scaffolding. Support that helps someone to do something they would not be able to do otherwise does not count as scaffolding if they still cannot do this alone once the support is removed. So offering the kind of support which is genuine scaffolding requires some careful judgement, and in particular for teachers to know their students – and their current abilities and potential for progression – well.

Fair enough, as teachers are generally intelligent, insightful and resourceful people- and ready to take up the challenge. But of course what I have described is a teacher supporting a learner: in a class or 25, 30, 40 learners there are 25, 30 or 40 individuals. Each learner has a certain level of current competence, and a particular potential to move on (which is sometimes labelled (after Vygotsky) their ‘zone of proximal development‘, ZPD), and specific characteristics as a learner – levels of confidence, self-belief, and so forth. The job of a teacher is to somehow support all these individuals so they can all be working within their own idiosyncratic ZPD.

The teacher can only do so much to individualise support by moving around the class talking to the students, and this raises the question of how readily teachers can provide learning resources which act as scaffolds (not just supporting students in completing tasks, but moving them along in the learning). I looked at two types of scaffolding resource (labelled scaffolding PLANKS and POLES) some years ago (Taber, 2002), but always felt it needed more attention.

I designed a resource intended to support student learning in one topic area,  understanding the nature of circular motion (that many students see as natural and unaccelerated motion) and some teachers kindly agreed to test it with their classes. Then analysis sat on hold due to too many other priorities, until Dr Richard Brock kindly agreed to join the project and lead on the analysis. This paper reports on this work.

The trial consisted of students in classes responding to one of two forms of a sequence of questions to see if those given a task intended to support developing understanding would increase their performance on a related task (compared with a control condition including a task of similar structure, but less pertinent to the learning objective). I won’t spoil the story(!) for anyone who wishes to read the chapter, but very briefly it seemed the materials were not ideally pitched for many of the students in the trial (many seemed to need greater support) but there was evidence of the resource helping some learners. Most of those completing the activity made little or no progress in their learning, but a minority seemed to be moved on quite a bit.

This simply reinforces the point that if support is to be scaffolding it needs careful tuning to different students. The study offers some kind of proof of concept for the type of resources tested, but reinforces the message that such resources need to be carefully designed, and then adjusted/matched to different student groups (i.e., within as well as across classes).

Bottom line: scaffolding tools can support learners as part of a strategy of differentiation by support.


Without whom…

Thanks are due to the anonymous teachers and students who helped by trying this out.


The abstract:

Scaffolding allows a learner to succeed in tasks beyond their current developmental level, through sharing in activities that can facilitate the learner to internalise that activity through social mediation. This guides the learner’s development towards autonomous success in the activity. The process is effective to the extent that the shared activity supports the learner in meaningfully engaging in, and eventually mastering, the activity. The notion of scaffolding was introduced in the context of a single child being supported by an adult who is giving them their full attention – where teaching, and so learning, can occur implicitly within the context of everyday interactions such as play. Extending the principle of scaffolding to the planning of teaching and the design of learning activities in formal whole-class contexts is challenging. The present paper reports one small scale study that explored an attempt to design materials using principles of scaffolding in an aspect of upper secondary physics known to present learning difficulties to students. An activity to potentially scaffold new conceptual understanding (a scaffolding POLE) was prepared to be undertaken after a short activity to reactivate prerequisite learning (a scaffolding PLANK). The materials were administered to students (n = 122, c.16-17 years of age) taking an elective upper secondary (high school) physics course. The results demonstrate the difficulty of estimating the level at which to pitch learning materials intended to scaffold learning, but also suggest that such materials may contribute to shifting student thinking even when they are not optimally ‘tuned’. The results of this small-scale study indicate both the difficulty and the potential of transferring the scaffolding principle from dyadic (e.g., parent-child or tutor-single student) contexts to formal classroom teaching.



Taber, K. S. (2002) Chemical misconceptions – prevention, diagnosis and cure, London: Royal Society of Chemistry


Scaffolding learning: principles for effective teaching and the design of classroom resources

cover Effective Teaching and Learning

Taber, K. S. (2018). Scaffolding learning: principles for effective teaching  and the design of classroom resources. In M. Abend (Ed.), Effective Teaching and Learning: Perspectives, strategies and implementation (pp. 1-43). New York: Nova Science Publishers.

This is one of two chapters (the other written with Dr Richard Brock) in this book considering the theme of scaffolding.


What is scaffolding?

The notion of ‘scaffolding’ is widely used in educational circles. The term was used by Bruner and his colleagues when applying ideas of the Soviet psychologist (and polymath) Lev Vygotsky on how education can support a person’s development.

When used correctly scaffolding refers to a kind of support given to a learner that enables to them to (a) successfully engage in activities that they cannot undertake unsupported, AND (b) begin to internalise new skills/knowledge such that they develop competence that will allow them to succeed in these tasks unaided in future.

In practice however the term scaffolding is often used much more loosely as if it is synonymous with supporting. So sometimes any support offered by  teachers is referred to as scaffolding, regardless of whether the learner needs it, or is developing towards competence through being supported.


Teaching in the zone

However,  I suspect this is because the technical use of scaffolding requires assessment of the learner’s potential (in term of what is technically known as their ZPD, or zone of proximal development) and careful design of matching support that can be faded (slowly reduced) as the learner comes to need less support, until they can manage without any scaffolding. That’s quite a challenge for teachers – especially as every child in a class is different.

The chapter discusses and explores these ideas, and considers the kinds of tools teachers might develop to put this kind of support, true scaffolding, in place. (The other chapter written with Richard discusses a small study to test out some of these principles.) It is hoped this treatment might be helpful for teachers who are intrigued by the idea of scaffolding but are not sure how to apply the idea in classroom teaching.


The abstract:

Within educational discourse, the idea that teachers should ‘scaffold’ student learning is extremely widespread, yet it is often less clear what this means in the classroom beyond the teacher structuring learning activities and offering students support. Many teachers associate the term with the educational thinking of Vygotsky, but they are often less clear what would comprise an effective teaching scaffold. This chapter reviews use of the term scaffolding in teaching and explains the purpose of scaffolding in the context of Vygotsky’s developmental theory. The chapter draws upon Vygotsky’s spatial metaphor for how learning activities could be positioned in relation to the learner’s current and potential levels of development. This activity ‘space’ is divided into three zones: scaffolding has potential to support learning that can facilitate student development, but only when the learning activity is located in the central zone (the ZPD) and is mediated through scaffolding. The chapter offers an analysis of the function of scaffolds, their role in classroom differentiation, and the logic of ‘fading’ (reducing scaffolding as learning proceeds). This suggests principles that teachers need to take into account in order to effectively employ scaffolding as a strategy in their teaching. Scaffolding can be based on direct mediation through dialogue between a learner and a teacher, but in classroom teaching there are severe constraints on how much one-to-one interaction each individual learner can access. Teachers wishing to scaffold learning therefore have to design learning activities and support materials that will place students in their ZPD. To illustrate this process, two distinct types of scaffolding tools are characterised in relation to different stages in the scaffolding of learning new conceptual schemes and frameworks.

Alternative Conceptions and the Learning of Chemistry

Alt Conceptions & tLoC

Taber, K. S. Alternative Conceptions and the Learning of Chemistry. Israel Journal of Chemistry, 0(0). doi:10.1002/ijch.201800046


The abstract reads:

A great deal of research has indicated that teaching is rarely a matter of introducing learners to material that simply replaces previous ignorance, but is more often a matter of presenting ideas that are somewhat at odds with existing understanding. In subjects such as chemistry, learners at school and university come to their studies already holding misconceptions or ‘alternative conceptions’ of subject matter. This has implications for subsequent learning, and so for teaching. This article reviews a number of key issues: (i), the origins of these alternative conceptions; (ii), the nature of these ideas; and, (iii), how they influence learning of the chemistry curriculum. These issues are in turn significant for guidance on (a) how curriculum should be selected and sequenced, and (b) on the pedagogy likely to be most effective in teaching chemistry. A specific concern reported in chemistry education is that one source of alternative conceptions seems to be instruction itself.


An invitation

This is one of those somewhat awkward articles – an invited article which none-the-less has to pass through and satisfy peer review. As the name suggests, Israel Journal of Chemistry is not an education journal but a chemistry journal. I was therefore pleased to learn that it was to have a special issue on Chemistry Education as often educational scholarship does not feature in mainstream natural science journals.

As a review article I was aware I had written quite a long piece, and felt that I needed to avoid it becoming over-long. The review process was supportive as recommendations from reviewers gave me the opportunity to develop some aspects further that I have initially felt I had space to do. I think the final review is better for that.

Whilst I was working on this review, Israel was in the news – once again – due to issues of conflict with its Palestinian neighbours. I am by nature a pacifist, but also not so stupid not to be aware that this is a luxury more easily afforded to someone who has never faced war, nor the kind of provocation that arises in major conflicts. Although I have been inconvenienced by terrorism in the UK, and have of course seen the outcome of it in the media, I have never lost a loved one or been injured or made homeless in such actions. It is very hard to fully appreciate the position of those who are directly affected by such issues (and I hope I never do). The State of Israel sometimes behaves in ways I consider completely unacceptable, but I also recognise that innocent Israelis are subject to totally unacceptable attacks as well. I appreciate the frustrations of the Palestinians in Gaza, without accepting this justifies terrorism. I also appreciate how people in living in Israel should not have to face terrorist attacks, but do not feel this justifies the Israeli state responding in ways that seem to many outside the situation to be little better than state terrorism and criminality.

I did wonder if publishing in a ‘national’ journal (the official journal of the Israel Chemical Society) might be considered as ‘taking sides’, or offering tacit support for the state Policies in Israel. However, I have professional friends and colleagues in Israel, and they have done nothing to deserve to be isolated from the international community. I am also something of an internationalist – I have always felt that the greater the cultural integration of people from different countries, the better the networking, and the more they work together to address common issues and problems, the harder it becomes for governments to take their peoples to war lightly. So, on balance, I am pleased to make a contribution.

The structure of the article is:

1. Introduction

2. Examples of Learners’ Alternative Conceptions in Chemistry (2.1 Some Examples of Common Alternative Conceptions in Chemistry; 2.2 An Alternative Conceptual Framework: the Octet Framework)

3. The Nature of Alternative Conceptions (3.1 Conceptions Vary in their Match to Canonical Knowledge; 3.2 Degree of Commitment to a Conception; 3.3 The Presence of Manifold Conceptions; 3.4 Degree of Integration of Conceptions; 3.5 Tacit Knowledge Elements; 3.6 Degree of Commonality of Alternative Conceptions; 3.7 Conceptual Change)

4. Acquiring Personal Conceptions (4.1 The Acquisition of Implicit Knowledge; 4.2 Cultural Facilitation of Learning; 4.3 Sources of Alternative Conceptions)

5. Implications of Alternative Conceptions for Learning (5.1 The Challenge of Class Teaching; 5.2 Working with Students’ Thinking)

6. Pedagogy that Takes into Account Alternative Conceptions (6.1 Diagnosing Student Thinking; 6.2 Responding to Alternative Conceptions: Working for Conceptual Change; 6.3 Recruiting Productive Facets of Student Thinking; 6.4 Explicitly Teaching About Models; 6.5 Teaching Informed by the History and Philosophy of Chemistry)

7. Summary and Outlook


Writing something new?

There is something of an inherent tension is constructing invited reviews of this kind. People are asked because they are considered to know something about the topic, which is usually based on being known for having written quite a bit about the matter already! So there is then something of a balancing act in writing reviews of this kind. To some extent they will re-tread previous writing on the same theme (as the perceived usefulness of such writing is why someone was selected to contribute on the topic). However, if a review simply reproduces work already published, then it does not really add anything to the topic.

The aim as an author then is to offer something more insightful, or organised in a more provocative or fruitful way, of with a new range, compared with earlier work on the topic. (I hope I have done so, but that is for others to judge.)

A particular issue here was  matter of audience. Some research reports, perspectives and reviews are written primarily for other researchers – with the intention of moving forward a particular research programme that a community works in. Other writing is intended primarily for non-researchers, practitioners such as teachers. Researchers and teachers bring different background knowledge, different expectations, even different lexicons to the writing. Writing for researchers is often expected to be technical (so almost curt); but for teachers to offer exemplification that links to their everyday classroom practice. The audience I was expecting here was primarily research chemists, most of whom have a teaching role in a university or research institution. The assumption was that many readers had limited exposure to educational ideas. I hope I have met the needs of the audience, but again that is for others to judge.


The use of Cronbach’s Alpha…

Cronbach alpha

Taber, K. S. (2017). The Use of Cronbach’s Alpha When Developing and Reporting Research Instruments in Science Education. Research in Science Education, 1-24. doi:10.1007/s11165-016-9602-2

This article was published Open Access in Research in Science Education, so can be freely downloaded by anyone. Like most of the top science education journals, Research in Science Education charges a subscription or download fee to readers, but does not charge authors for publication. However, I found that my University had some existing agreement with the publisher (Springer) that allowed me to publish this article Open Access without paying a fee.


The abstract reads:

“Cronbach’s alpha is a statistic commonly quoted by authors to demonstrate that tests and scales that have been constructed or adopted for research projects are fit for purpose. Cronbach’s alpha is regularly adopted in studies in science education: it was referred to in 69 different papers published in 4 leading science education journals in a single year (2015)—usually as a measure of reliability. This article explores how this statistic is used in reporting science education research and what it represents. Authors often cite alpha values with little commentary to explain why they feel this statistic is relevant and seldom interpret the result for readers beyond citing an arbitrary threshold for an acceptable value. Those authors who do offer readers qualitative descriptors interpreting alpha values adopt a diverse and seemingly arbitrary terminology. More seriously, illustrative examples from the science education literature demonstrate that alpha may be acceptable even when there are recognised problems with the scales concerned. Alpha is also sometimes inappropriately used to claim an instrument is unidimensional. It is argued that a high value of alpha offers limited evidence of the reliability of a research instrument, and that indeed a very high value may actually be undesirable when developing a test of scientific knowledge or understanding. Guidance is offered to authors reporting, and readers evaluating, studies that present Cronbach’s alpha statistic as evidence of instrument quality.”


Why write a paper about a statistic?

Most of my research uses qualitative methods such as interviewing, and I do not see myself as an expert in quantitative methods. So writing about a statistic seems an odd choice (and perhaps even a very dry choice of topic). Indeed, I did not initially know much about Cronbach’s alpha, except I had noticed it was often used in studies.

My motivation to write about Cronbach’s alpha did not derive from my own research programme, or even from my teaching about research methodology. Rather, it came from work as a reviewer and editor. Being asked to review studies submitted for publication I found that Cronbach’s alpha was being used, and values reported as justifying the value of the instrument used. These papers seldom offered an argument beyond – to paraphrase – “alpha was >0.70 so the instrument is reliable”. So to do my work as a reviewer I found I needed to go and read up on alpha, and indeed find out what Cronbach thought alpha was about.

So what does alpha measure?

Two of the key things I learned were that alpha measured internal consistency, rather than reliability as it is normally understood (seeing if one gets the same result when repeating a measurement), and so it was only meaningful when applied to an instrument with a range of items intended to measure a single construct. So where an instrument has several scales, it only makes sense to use alpha separately for the individual scales, not for all the items pooled together.

The other key point seemed to be that there was no strong logic with using 0.70 as a cut-off. The higher the value of alpha, the more the different items are eliciting the same responses from people completing the scale. A low value means that the items are not getting at the same thing. A very high value means people are responding to the different items in pretty much the same way (different people are responding differently, but each person is responding to the scale items in a consistent way) – and perhaps suggests there is too much redundancy, and some of the items could be dropped without undermining the instrument. (If one had a perfect item that elicited exactly the construct being tested from everyone, then there would be no need to use more than one item as a scale. Of course, that does not tend to be the case – but having more items than are needed {as Cronbach recognised} does not add anything other than requiring more time and effort in completing, and analysing, an instrument.)

An important point is that alpha very sensitive to the number of items in a scale. A high value of alpha for a scale with three items suggests these items are well aligned, but the same value for a scale with 25 items would be much less persuasive. It is fairly easy to increase the value of alpha by adding more items – as long as those items are perceived very similarly to some of these already in the scale.

To offer a facetious hypothetical example. Imagine a scale of ten items where alpha was found on an administration (the value only applies to a specific administration to a particular sample, not to the scale itself) 0.69, and that was considered just below the required level of ‘reliability’. If one of the items read “I very much enjoy using the Bunsen burner”, then adding another item that reads “I enjoy using the Bunsen burner very much” would have almost certainly led to the value of alpha having instead been >0.7 and the scale being judged ‘reliable’. The statistic is very fickle to this kind of manipulation.

Evidence of poor practice

I found that some of papers I was asked to read as a reviewer, or sometimes those I saw as an editor, used alpha in ways that seemed inappropriate, and often without any apparent understanding of what alpha did and why it might be useful: simply calculating, hoping it was more than 0.7, and reporting it in the paper, seemed to be seem as important.

Authors were in effect saying “this is a good instrument because alpha >0.7” even when it was inappropriate to use alpha. Commonly alpha would be calculated across diverse scales in an instrument, or alpha would be calculated for a wide-ranging knowledge test where clearly the items (questions) were testing understanding of a range of concepts and principles.

So having done some reading to find out about alpha, it seemed that most of the examples I then met in science education papers used alpha without explaining what it was or why it was used, and often authors seemed to use alpha where it was not relevant or helpful. Moreover, this applied to examples I saw in published studies in good journals, as well as manuscripts submitted for review.

This motivated me to write an article explaining what alpha was, and why it was introduced, and when it should be used, and what we should read into the values calculated. I drew on examples from the published literature to explain appropriate use, and the limitations and flaws in many published studies.

Improvement of the article in peer review

The original manuscript submitted for publication drew upon specific published articles to make particular points about how alpha was being presented in science education studies. I felt the article worked well that way. However, one of the reviewers for Research in Science Education, made a fair point that in writing the paper I was largely, for my examples, picking on published studies that showed flaws: this could be seen as relying on anecdotes rather than being systematic.

To address this I surveyed the four top science eduction journals over the most recent complete year of publication to identify every use of alpha. Whilst, as might be expected, this revealed some good practice, it also showed just how inconsistently authors described what alpha was testing, and how qualitative interpretations of the actual values calculated varied wildly. This lengthened and changed the feel of the paper (from originally being a kind of perspective article, to being arranged around a formal study offering more specific evidence of current practice). I was initially a little uneasy about this at the time, having felt the earlier version had more ‘punch’. However, on balance. I feel the reviewer offered good advice. I do think that responding to the recommendation strengthened the paper, so that it offered a more robust evidential basis for offering specific guidelines for others using Cronbach’s alpha in their studies.

Personal ignorance can motivate a move towards greater expertise

So that’s how a largely ‘qualitative researcher’ came to publish a paper about statistics. I did not initially understand the basis or purpose of Cronbach’s alpha, but the need to find out in order to effectively review manuscripts led me to realise that a lot of those researchers actually using Cronbach’s statistic do not seem to really understand it either.


Revisiting the chemistry triplet…

Revisiting the chemistry triplet

Taber, K. S. (2013). : drawing upon the nature of chemical knowledge and the psychology of learning to inform chemistry education. Chemistry Education Research and Practice, 14(2), 156-168. doi:10.1039/C3RP00012E

This is a perspective article published in Chemistry Education Research and Practice, which is a free access journal – anyone can download the article.

The title refers to the idea in chemistry education that teaching (and learning) involves the macroscopic level (what is seen and handled at the bench), the sub-microscopic level (theoretical models of atoms and molecules, etc.), and the system of subject-specific symbols used by chemists to represent chemical ideas (such as chemical formulae).

This was first pointed out decades ago by the late Alex Johnstone, and it has been widely recognised that teaching across these ‘three levels’ makes the subject challenging for students. This has come to be seen as one of the central ideas in chemistry education, as it is considered that it offers teachers a way to think about the complexity of what they are presenting to students, and asking them to make sense of.  “Revisiting the chemistry triplet…” offered an updated perspective on this theme.


The abstract reads:

Much scholarship in chemical education draws upon the model of there being three ‘levels’ at which the teaching and learning of chemistry operates, a notion which is often represented graphically in terms of a triangle with the apices labelled as macroscopic, submicroscopic and symbolic. This model was proposed by Johnstone who argued that chemistry education needs to take into account ideas deriving from psychological research on cognition about how information is processed in learning. Johnstone’s model, or the ‘chemistry triplet’, has been widely taken-up in chemistry education, but has also been developed and reconceptualised in diverse ways such that there is no canonical form generally adopted in the community. Three decades on from the introduction of Johnstone’s model of the three levels, the present perspective article revisits both the analysis of chemical knowledge itself, and key ideas from the learning sciences that can offer insights into how to best teach the macroscopic, submicroscopic and symbolic aspects of chemical knowledge.


Key points

The presentation in this article draws upon the idea that it may be helpful not to consider the three ‘levels’ as entirely discrete, as the symbolic level actually has a useful ambiguity (as formulae and chemical equations can refer to both substances, and to molecules) and so often acts as a bridge between the macroscopic and submicroscopic levels. It is useful to be able to talk about, say hydrogen chloride the substance, then write HCl to represent that, but to also see that as also representing a molecule as well as a sample of material. However,  if teachers use this affordance to shift between these two levels without being explicit about what they are doing, they can confuse learners.

The article also emphases a point sometimes missed when thinking of the triplet, which is the shift made between the actual phenomena observed and the theoretical language used to conceptualise and describe those phenomena. So students see crystals ‘disappear’ in a liquid, or something change colour, or give off smoke, and this gets redescribed as combustion or a redox reaction or a substitution or whatever. So there are two macroscopic levels of description: one in terms of phenomena as observed, and the other in terms of the formal chemical description – which can often be represented in symbolic language in a way that also represents an account of how the process is understood at the level of molecular interactions. Teachers of course, as experts, have often learnt to see phenomena in theoretical terms – they have learnt to short-cut the need to work to reinterpret what is seen, heard, and smelts in terms of formal concepts.

In part, the paper was meant to suggest to other chemistry education scholars that it might be time to refine the way we discuss and use the triplet in thinking and writing about the challenges of chemistry teaching and learning. However, I also hope the paper is sensible to classroom teachers of chemistry (whether chemists or other science teachers), and that it is useful in helping them reflect on how our teaching can overwhelm some students; and – more positively – how we can make the triplet explicit to help model to students something of the way chemists think about the world.