Clothespin Math on a clothes hanger! LOVE this. Easy to make, and self explanatory. I'm thinking a wire clothes hanger would work better, so the clothes pins are easy to slide back and forth (almost like an abacus).
Dry erase on plastic plates, hmm. From previous pinner: Perfect for math in focus number decomposition! Use a plastic plate and you can write with dry erase! Great to teach part part whole, fact families, etc.