This stuff is great. I’ve been teaching a slightly-harder-than-usual logic course this semester and I really wanted a blackboard for my office, for practicing proofs on.
One of those things that I think good logic students quickly realise is that it’s one thing to be able to follow a proof in class, and quite another to be able to reproduce it yourself in homework or on a test. Well one of the things that I’ve learned from teaching logic is that it is one thing thing to be able to scribble a proof out on a notepad, and another to be able to present clearly on a blackboard during a lecture.
Why? Well, it has something to do with the fact that one’s notepad is uebersichtlich – scrawling out some complicated instance of an axiom isn’t that hard if the axiom is at the top of your page, but it can be a bit harder when that axiom is 2 blackboards back, or on the other side of the room. (My logic classroom has 6 huge boards that scroll past each other – I rather like that, but it can make it easy to loose the first part of a proof.) So I think that for me to write a proof on the board requires that I know more of the proof off by heart than when I’m just writing it on paper. Second, of course, there’s just more pressure when 30, or 60, eyes are on you, all waiting to be reminded what the induction hypothesis 2 boards ago actually was. And third, when I’m putting a proof on the board I’m often talking at the same time. And as teachers everywhere know, talking goes faster than writing, so you’re basically running two trains of thought at once anyway.
So I’d been yearning for a blackboard in my office, and then I found this stuff. . It consists of flexible blackboard tiles that stick to your wall (they’re removable and re-positionable- they come off my white-painted wall easily, without leaving a mark, and stick right back on, and, surprisingly, it’s really easy to write on them with chalk and clean them off. (I imagine if your wall is a different colour from your chalk you’ll end up with a chalk-coloured “halo” around the board though.) They’re a bit smaller than they look in the photo – each tile is about the size of a US letter sheet of paper – and I ended up buying 2 packs of 4. Also, I think the tiles are a little prone to getting scratched by the chalk – I can imagine having to buy some more after a couple of years or so. But they look great on my wall and they do the job (every Tuesday and Thursday morning before my logic lecture…)