A clean slate

Figure 1 – Forward-facing view of the main blackboards in the seminar room in the university’s Higgs Centre for Theoretical Physics. Photo credit: R Galloway.

In this post, Dr Ross Galloway, a Senior Lecturer in the School of Physics and Astronomy, reflects on the place of the blackboard in the modern classroom….

Whenever I have been involved in consultations over the last few years about the refurbishment or construction of lecture theatres, a surprisingly consistent bone of contention has been the provision of writing surfaces, namely blackboards. It turns out that physicists and mathematicians (and I’m sure others too) have very strong views about blackboards; many of my colleagues list the presence of a blackboard as a non-negotiable requirement for suitable teaching rooms.

As a number of long-suffering people have pointed out, from media technology experts to estates coordinators to architects, blackboards are tricky things. It’s not easy to source high quality blackboards these days, they constrict the layout of teaching spaces (since they have to be on the front wall, and you have to be able to access them to write on them), there can be very difficult trade-offs in accommodating them alongside high resolution projection screens, and the inevitable clouds of chalk dust don’t play well with AV equipment. So why is there such an insistence on this ancient technology? Why the obsession with chalk?

In recent years, the phrase “chalk and talk” has taken on some rather unfortunate pejorative connotations, summoning up images of stuffy, old-fashioned and out of date teaching methods. Readers of my previous Teaching Matters posts will have seen that I am a proponent of the flipped classroom and active engagement teaching approaches. Surely, then, I should eschew chalk and talk, and all that it entails?

Well, I don’t. My lecture sessions typically feature about half of their duration spent on interactive engagement activities, and it is natural to focus on those aspects. However, it’s easy to overlook the remaining half, which involves me speaking directly to the class in a way that would have been recognisable to students for centuries.

An extended argument

A central component of physics and mathematics is the development of extended formal arguments, be they the derivation of an important formula, or the formal proof of a mathematical proposition. These often involve the interplay of multiple components of an argument, or the interweaving of disparate strands of equations. Here, blackboards give a simple but vital contribution: they provide a large amount of visual real estate, allowing the class to see the whole argument at once. This eases the cognitive load because the students don’t have to try to remember lots of previous steps in the argument.

Blackboards also allow non-linear approaches to the argument. For example, the instructor can start a complex diagram with only the necessary initial elements, then return to it later to embellish it as the argument develops. Thus, the students’ attention can be drawn to those aspects that are currently relevant, without overloading them. Crucially, it also allows the instructor to model expert modes of thinking, showing how an argument develops step by step, and why they do things in that particular order. It is not unusual at all for a physics or mathematics lecturer to be writing the later steps of a derivation on the bottom right board, and still be referring back to previous results on the top left board. We really do need the whole wall to write on. This scene from the film A Serious Man plays it for laughs, but this is only partially an exaggeration…

Figure 2 – Physics lecture from A Serious Man (2009). From https://i0.wp.com/thestand-online.com/wp-content/uploads/2017/02/physics-classroom-blackboard.jpg?w=1920&ssl=1

Seeing the whole pitcher

If this all seems a bit abstract, indulge me in a sports analogy. For many years, I didn’t understand the appeal of watching baseball at all. I had only ever seen short snatches of baseball games on TV, and it seemed baffling and tedious. Then, while visiting the US, some friends dragged me along to an actual ball game, and I discovered that it was captivating. The trick is that you have to be able to see the whole baseball field at the same time. You watch the pitcher winding up, you watch the hitter readying himself, you can see the fielders repositioning, you know which bases are loaded and which aren’t. Will the player on second try to steal a base, or will he stay where he is? It only makes sense when you can see the whole picture, and the TV cameras only ever show a little slice at a time. I just didn’t understand baseball until I could see it all at the same time, and in many ways physics and mathematics are just the same (cricket may be similar too; I’ve never been to a cricket match).

non-traditional technologies: It’s not black and white

Fair enough, so we need the board space. But can’t more modern technology do the same? Well, whiteboards are awful. Whiteboard pens have a half-life measured in seconds, and always run dry and go faint in the middle of what you’re trying to do. Whiteboards also need a disciplined regime of cleaning to stay at their best, which is not always compatible with the hurried scrub as the next lecturer hovers near the door.

I have had good mileage out of visualisers (sometimes also called ‘document cameras’), which project a camera image of a written page onto the screen. You can use your natural handwriting on them, so don’t need to develop a ‘board hand’, and you also naturally face the class while writing, which is good for eye contact and interaction. However, working space is the killer issue here. You can project about half a side of A4 paper at once. I’ve found this sufficient for my first year course, marginal at best for second year, but not enough for more advanced courses. The aspect that most strongly pushed me towards the visualiser was that it used to be the only way to capture handwritten elements on lecture recordings. However, the introduction of the really rather excellent chalkboard capture in suitably equipped rooms has now changed this situation.

Chalking it up

As well as these pragmatic considerations, it would be wrong to deny that there’s an element of tradition, bordering on a shibboleth, to the use of blackboards in physics and mathematics. There’s a tactile pleasure to writing on a quality surface with good chalk (indeed, a recent chalk shortage caused ripples of alarm in the global mathematical community.) In Figure 1, we can see the main blackboards at the front of the seminar room in the Higgs Centre for Theoretical Physics, handily illustrating how the blackboard real estate has been exploited to the full. Figure 3 shows a side view of the same room, with one of the Centre’s most prized features, a continuous wall of blackboard.

Figure 3 – Higgs Centre side blackboards. Photo credit: R Galloway.

After a seminar, it’s common to find small groups of interested people clustered along this wall, thrashing out some theoretical physics on the blackboard. One of our responsibilities as educators is to model authentic professional discourse, and the blackboard is a central tool of cutting edge physics and mathematics. Breakthroughs can and do occur with chalk in hand!

So if ever you find yourself wiping stray chalk dusk from your clothes, or wondering why the slide projections have to share a wall with the black monolith from 2001, then it’s not because some elements of the university community are being old-fashioned, inflexible or reactionary. Sometimes, blackboards just are the right tool for the job.

Ross Galloway

Ross Galloway is a Senior Lecturer in the School of Physics and Astronomy. He teaches on the undergraduate programmes in physics and also conducts pedagogic research as a member of the Edinburgh Physics Education Research group (EdPER). His research interests include the development of student problem solving skills, diagnostic testing, and flipped classroom pedagogies.


  1. Thanks Ross, not only for convincing me of the value of chalkboards but also reminding me of the power of good writing!

  2. I’m curious how other intuitions teaching mathematics seem to manage while not having a single blackboard? I understand the argument that a writing surface is important but I’m not sure why it has to be chalk?

    • As I mentioned in the post, it doesn’t have to be chalk. As you say, the writing surface area is really the thing that matters. You can use whiteboards, or anything else that provided that large area. It’s just that lots of people feel that chalk is a nicer experience in many ways. It’s a personal preference thing.

  3. […] One of my favourite posts is A Clean Slate by Dr Ross Galloway. I loved how much traction it gained on Twitter and I could see by the comments and likes the post received that it engaged a lot of people, which is exactly what we want Teaching Matters to inspire: A clean slate – Teaching Matters blog […]

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