Here are a couple of things you might have seen before.

How on earth do these things work. And what do they have in common?

    • More missing square puzzles. (My favourite is the one right at the bottom with the rotating pieces.)

    • Here is a fantastic video explaining these things from a former colleague of mine in Australia who is now a youtube star - as far as you can be one with math :)

    • Try to understand as many aspects of this as you can. Especially how the Fibonacci sequence is useful in constructing these things.