SIGCSE Oh, oh, oh, it’s magic!

If you’re at SIGCSE, then you’re probably one of the 1,000,000 people who jammed into the pretty amazing Wednesday session, Demystifying Computing with Magic, with Dan Garcia and David Ginat. Dan and David coped very well with a room that seemed to hold more and more people – in keeping with a magic show, we were all apparently trapped in a magic box.

The key ideas behind this session was that Dan and David would show us five tricks that would teach or introduce important computing notions, such as discrete maths, problem representation, algorithmic patterns and, the catch-all, general notions. Drawing on Silver’s 1997 paper, Fostering Creativity Through Instruction Rich In Mathematical Problem Solving and Problem Posing (It’s better in German, trust me), they focused on the notions of fluence (diverse directions for exploration), flexibility (adaptation to the task at hand – synonymous with cognitive flexibility), originality (unfamiliar utilisation of familiar notation), and awareness (being aware of the possible fixations[?] – to be honest, I didn’t quite get this and am still looking at this concept).

The tricks themselves were all fun and had a strong basis in the classical conceit of the stage magician that everything is as it seems, while being underpinned by a rigorous computational framework that explained the trick but in a way that inspired the Gardernesque a-ha! One trick guaranteed that three people could, without knowing the colour of their own hats, be able to guess their own hat colour, based on observing the two other hats, and it would be guaranteed that at least one person would get it right. There were card tricks – showing the important of encoding and the importance of preparation – modular arithmetic, algorithms, correctness proofs and, amusingly, error handling.

Overall, a great session, as evidenced by the level of participation and the number of people stacked three-high by the door. I had so many people sitting near my feet I began to wonder if I’d started a cult.

The final trick, Fitch Cheney’s Five Card Trick was very well done and my only minor irritation is that we were planning to use it in our Puzzle Based Learning workshop on Saturday – but if it’s going to be done by someone else, then all you can ask is that they do it well and it was performed well and explained very clearly. It even had 8 A-Ha’s! That’s enough to produce 2.66 Norwegian pop bands! If you have a chance to see this session anywhere else, I strongly recommend it.

(A useful website,, was mentioned at the end, with lots of resources and explanation for those of you looking to insert a little mathemagic into your teaching.)