This is the final part of my talk from ResearchEd Rugby in July. You can also read about some of this in my EiC article. In the first part, I talked about lightbulb moments: how precious they are to witness, and how I thought Threshold Concepts might be the key to these moments of enlightenment. They’ve been described as portals to new and greater understanding, allowing access to conceptual understanding that was previously inaccessible. In my second post, I talked a bit about how I approach research: how I evaluate it, and how I try not to significantly increase my workload or go “off-piste” when I apply it to my practice.

I wanted to identify conceptual stumbling blocks in KS4 Structure and Bonding, so I used misconceptions literature to compile a list of tricky concepts, and designed questions to test pupils’ understanding of them.

Are you sure about that?

I used in-class assessment to monitor how successfully these concepts had been embedded, and this informed the direction of lessons and questioning in-situ. But I also used True/False questions with in-built confidence measures (see this post) to determine the relative strength and pervasiveness of misconceptions.


I colour-coded students’ answers, and they calculated “confidence scores” before annotating their incorrect answers to aid metacognition. This was done using Google Forms, which I use quite often as I find them very useful for receiving, as well as giving feedback, so this was very close to “business-as-usual” for both me and my pupils, with just an extra level of analysis built in. As I said in my second post, it was very important to me, from the point of view of workload and ethics, that I didn’t do (or expect my pupils to do) anything that they wouldn’t have done anyway, within the normal course of teaching.


Action research? Or just reflective teaching?

I’m not claiming that any of this was sufficiently valid, robust, reliable or unbiased to be used or applied in any other context than my own classroom or with my particular cohort of pupils. My aim was simply to improve my teaching, and hopefully to anticipate some ways to better support future pupils. Having said that however, there were certain concepts that proved more “troublesome” and pervasive than others, and I think they highlight some key points that are perhaps more general.


Using pupil answers from 4 classes that I happened to be teaching at the time (Y10 top set triple, Y10 middle set double, Y11 top set triple, Y12 mixed), I measured the confidence difference of each concept tested (difference between the total confidence scores for right and wrong answers). A large confidence difference indicates a relatively high proportion of correct answers with high degree of certainty from students. Combining the scores from each concept or four KS4-5 classes enabled me to order the concepts by relative difficulty.

confidence difference table
Confidence difference by relative difficulty (NB: chlorine/ chloride corrected on Q sheet)

Troublesome ideas in Ionic Bonding

Students found key concepts in ionic bonding particularly problematic. Dot/cross diagrams can give students a picture of “ionic molecules”, with a localised charge located in the top right hand corner of each ion, and with each ion forming discrete bonds with 1-3 other ions.

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But they must understand that:

  • ions are attracted to any oppositely charged particle
  • ions carry a charge that is distributed throughout the ion and acts in all directions
  • ions form a giant 3D lattice (when solid) containing millions of ions
  • ions remain as ions, whatever their physical state, including in aqueous solution

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Taking this into account, I’d suggest the following when teaching ionic bonding and structure:


Hurdles and Bottlenecks

So do any of these troublesome ideas count as true Threshold Concepts? I’m not ready to presume enough understanding to identify these yet. However, there were 3 key ideas that certainly prevented pupils from developing a greater understanding until they had understood them. So I’ve called them “bottlenecks”, as they hold pupils up, and prevent them from moving on until they’ve mastered them.

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The third bottleneck (as I said in my first post) was a bit of surprise, but it illicited a few definite lightbulb moments when I clarified the idea with pupils. And I think it underlines the point that Cousin makes, that “One of the difficulties teachers have is that of retracing the journey back to their own days of ‘innocence’, when understandings of threshold concepts escaped them in the early stages of their own learning.”

For this reason, I think it’s going to be difficult to identify true Threshold Concepts ourselves (as teachers). We’re very good at idetntifying “big ideas” and “key concepts”, but this is always from the point of view of “masters” and “experts”. I really believe we can only identify the true sticking points for pupils is by talking to them!

Mimicry vs Mastery

My final thoughts on this are not fully formed. It’s evident that the path to true mastery is not straightforward, and it involves a degree of insecurity and re-visiting to achieve true mastery. I’ve written more about this here, and it’s something I’m still thinking about. Slide26

Interestingly, my “triple 10s” seemed to retain ideas much more strongly than my “double 10s”. My colleague hypothesised that this might be because they have taken the troublesome journey to truly mastering the concepts, rather than resorting to mimicry (to just get the mark in the exam at the time) as my “doubles” might have done. I will think on this further…