There is a lot of content in the new GCSE curriculum and in chemistry the problem is particularly acute. I’ve found it challenging finding time to teach everything to the depth that I’d like to teach it. There is so much for students to learn, and I worry they won’t be able to remember it all, let alone apply it, when they come to sit their exams at the end.

So what, as GCSE teachers, should we do? In an ideal world, I would have the time and space to stick with every single idea and concept that I teach until I was fully confident that all students had grasped it fully. That’s just not practical.

Instead, experience has taught me that, rather than rushing through the course to ensure everything in the specification is covered and given the same amount of time, it’s better to spend more time focusing on fundamental ideas and key concepts. Generally, I have relied on my own judgement to identify the aspects that need most emphasis, but I wanted to see if there was any research that could help me target areas more effectively. That’s how I discovered “threshold concepts”.

Changing outlooks

As a science teacher, I’m familiar with the idea that learning is cumulative, and certain concepts need to be understood before other things can be learned. And I’ve seen how a whole range of linked ideas will suddenly click into place when tricky concepts are finally mastered. So I was intrigued by the idea of threshold concepts, which have been described as “portals to new or transformed understanding”, because they are meant to change your outlook on the world once you’ve encountered them (Meyer and Land, 2003).

I think of them as those troublesome ideas that induce lightbulb moments when fully understood. Once mastered, they’re irreversible, and there is no return to your former naive view of the world. These are the foundation blocks that we should spend time on, speeding up the process of understanding for other areas of the curriculum.

I searched for a list of threshold concepts for a topic I was due to teach, hoping that by emphasising these view-changing ideas, I might unlock students’ understanding, and free up the potential “bottle-necks” that prevent them from moving on later. But I was disappointed to find that this list didn’t exist, and I would have to compile my own.

However, according to threshold concepts literature, this can be tricky for experts (as teachers are) because we tend to have forgotten our naive understanding (or misunderstanding) of the science we’re teaching (Cousin, 2006).

For example, it hadn’t occurred to me that I should underline how dot and cross diagrams, showing one or two ions, actually represent billions of ions in a typical reaction. It was only through conversations with students that I realised they hadn’t appreciated this, and this disconnect in understanding was preventing them from understanding everything fully.

Mission impossible?

So research into common student misconceptions was particularly helpful in my mission: it helped me to “retrace the journey back to innocence” (Cousin, 2006).

Using this research (eg Kind, Taber), I compiled a list of tricky concepts, and taught these ideas explicitly. I also tested students’ understanding of them via my usual assessment activities, which was really useful, because it highlighted the misconceptions that were most deeply entrenched. These were the ideas that would require the most work to help students to understand them, and I was able to plan accordingly. I had found my threshold concepts.

However, it became apparent that these truly transformative concepts were few and far between. Furthermore, breakthroughs in understanding are often hard-fought, and the point where students understand something permanently can be difficult to assess. So often, students appear to understand something when first taught it, only to have seemingly forgotten everything when they need to build on it for later topics.

So I think it’s important to consider what we actually mean by learning, because although it’s relatively easy to measure performance in a question or a test, this doesn’t necessarily indicate long-term, robust understanding.

Useful tool

This, and the difficulty in identifying threshold concepts, does not mean the idea is not useful. Admittedly, threshold concepts have been criticised for lacking in specific empirical evidence, and I understand this criticism, especially as irreversible mastery can feel elusive at times. But I’m a pragmatist, and they were a useful tool for unpacking the curriculum and developing my use of misconceptions research in general. This knowledge and understanding of student misconceptions by teachers has been identified as the characteristic that has the most significant impact on pupils’ progress (Neumann, 2014). It is also one of the recommendations in the recent Guidance report for science (EEF, 2018). So my reading and research in this area was incredibly valuable, even if the pure idea of threshold concepts remained elusive.

Consequently, for every topic I teach, I now try to identify common misconceptions, and use low-stakes assessments that specifically test understanding of them. I encourage students to be patient during inevitable periods of uncertainty, and reassure them that it’s normal not to understand everything immediately. I keep in mind that assessment activities don’t necessarily indicate irreversible understanding, and I revisit key concepts repeatedly, using a variety of contexts and question types.

If I’m honest, I don’t think I’ll ever have enough time to teach everything I want to teach in the depth I’d really like to teach it to, but I think that’s just the nature of teaching and a characteristic of teachers. We want everybody we teach to understand absolutely everything perfectly, and I’m just not sure how realistic this is within the constraints we work every day.

But I do now have much more confidence to focus on certain aspects of the curriculum more than others, and threshold concepts were a useful framework for shaping my planning and determining the foundational, underlying ideas.

Dr Niki Kaiser is network research lead at the Norwich Research School at Notre Dame High School