Confused? Good. You might be about to learn something.

Entropy can be confusing, but that might be a good thing. Credit: Flickr/TZA, reproduced under a Creative Commons licence.

It’s never the most comfortable of feelings to have some aspect of your work described as “appalling”. But that’s what greeted me yesterday morning when I scanned down the comments thread for the most recent video I’ve made with Brady Haran for his Sixty Symbols channel

The source of the opprobrium? Well, the video in question was on the topic of entropy. I should have learned by now not to go near the topic of entropy with a barge-pole for a YouTube video because it’s a subject that really can’t be done justice in five or ten minutes. But I had attended a brilliant and inspiring colloquium by Daan Frankel on entropy and self-assembly shortly before the video was filmed. As part of his talk Daan had described the pioneering work done by Sharon Glotzer’s group at the University of Michigan on the role of entropy in the self-organisation of nanoparticles. Glotzer’s group has neatly shown how entropy can be exploited to drive an ensemble of nanoparticles to an ordered state.

Yep, that’s right. Entropy produced order, not disorder. (I enthusiastically
recommend Glotzer’s TEDx talkfor more on this.)

I thought that this departure from the traditional view of the role of entropy would make a great subject for a Sixty Symbols video and suggested it as a topic to Brady. We filmed it and, as ever, Brady and I had some healthy and robust debate about the role of analogies and metaphor in explaining the physics. Overall I was pretty happy with how the filming went. (As I’ve discussed elsewhere, we academics do not get involved with the editing of the Sixty Symbols videos – that’s all expertly done by Brady. The first time we see the finished product is when it goes online.)

So why does YouTube commenter TheRumpus feel so strongly that the video doesn’t work? Well, you can of course read his comment for yourself but it was the final two lines which particularly resonated with me (for reasons I’ll go into below):

As I’ve explained over at YouTube, Sixty Symbols videos – certainly those with which I am involved – are not meant to be tutorials or mini-lectures. No-one should expect to come away with a solid understanding of entropy on the basis of watching a YouTube video (otherwise why would we bother with setting problems, coursework, lab work, and/or projects for thermodynamics courses – or, indeed, any aspect of physics?). Sixty Symbols videos are instead a conversation with physicists about particular topics that interest and enthuse them – they represent a taster, rather than a tutorial. (I discussed my qualms about YouTube edutainment in a physicsfocus post last year.)

Leaving those points aside, TheRumpus’s comment raises a much broader and rather more subtle issue. Is adding to confusion necessarily a bad thing? Should we always avoid the possibility of confusing the audience when we’re discussing or explaining physics? Or could confusion actually aid the learning process?

That certainly seems like a rather, errmm, unhinged set of statements for a university lecturer to make. After all, don’t I aim to make my lectures as clear as possible so as to enhance student learning? Don’t I revise and re-revise the notes I give students in an attempt to eliminate any hint of ambiguity? And isn’t the quality of my teaching assessed (via, for example, Student Evaluation of Teaching questionnaires) on the basis of its clarity?

Yes to all three questions. But could this focus on eliminating confusion and ambiguity actually be doing students a disservice?

A fascinating article was published in The Chronicle of Higher Education back in August on exactly this topic. In “Confuse Students to Help Them Learn”, the work of Derek Muller, of Veritasium fame, and both Sidney D’Mello (University of Notre Dame) and Arthur Graesser (University of Memphis) on the role of confusion in learning is described. D’Mello and Graesser’s work challenges much of the received wisdom about teaching and learning and I’ve made time over the past couple of weeks to read a number of their publications (which are all available here).

The title of a paper published earlier this year by D’Mello, Graesser and colleagues nails their colours to the mast: “Confusion can be beneficial for learning”. The abstract does a very good job of bringing out the key points of their study. Here’s an extract:

“Confusion is expected to be more the norm than the exception during complex learning tasks. Moreover, on these tasks, confusion is likely to promote learning at deeper levels of comprehension under appropriate conditions”

This flies in the face of everything we’re told about the characteristics of effective teaching, but, I suspect, will nonetheless chime with many physicists’ experience of how they came to understand complicated concepts in, for example, quantum theory, relativity, and – oh, let’s say – thermodynamics and statistical mechanics.

Over a decade before D’Mello et al.’s paper was published, Kurt VanLehn and co-workers had found that in order for successful learning to take place in physics, an ‘impasse’ (as they describe it) has to be reached. In other words, the student must be confused at some point in order to learn.

Or, as Derek Muller puts it in that Chronicle of Higher Education article:

“It seems that, if you just present the correct information, five things happen. One, students think they know it. Two, they don’t pay their utmost attention. Three, they don’t recognize that what was presented differs from what they were already thinking. Four, they don’t learn a thing. And five, perhaps most troublingly, they get more confident in the ideas they were thinking before.”

So, “add[ing] to the confusion about entropy”, as TheRumpus puts it, need not necessarily be a bad thing. What is of key importance, of course, is the student reaction to that confusion. We need to be very careful to ensure that the learner does not switch off entirely (and D’Mello and Graesser are at pains to stress this).

But when confusion triggers a response like the following, it’s difficult to argue that we should always aim for maximum clarity:

“Time to do some reading on this.” What more does any teacher want to hear?

Philip Moriarty

Philip Moriarty is a Professor of Physics at the University of Nottingham. His research interests lie in what has occasionally been described as “extreme nanotech” in that he works alongside a talented bunch of nanoscientists to prod, poke, push, pick, and pull individual atoms and molecules in order to explore forces and interactions down to the single chemical bond limit. Moriarty also has a keen and long-standing interest in science communication and public engagement. He is a member of the Sixty Symbols team that was awarded the Institute of Physics Kelvin prize in 2016 for “innovative and effective promotion of the public understanding of physics”. While he doesn't share his infamous namesake's fascination with the binomial theorem, Moriarty enjoys exploring the maths-music-physics interface including, in particular, the deep and fundamental links that exist between quantum mechanics and heavy metal music (a theme discussed at length in his book, “When the Uncertainty Principle Goes to 11”). He blogs at

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