Here’s the latest kids’ math book I picked up at the library.
Mental Math Challenges
by Michael L. Lobosco
As usual I am learning more from it than I think my kids will (see: math is such a vast subject that even a guy with a Ph.D. in it can pick up a kids book on math and learn stuff he never knew). It’s got tetraflexagons, arithmetic with scissors. I’ve done math with scissors, but it was always some form of topology. Anyway, check it out. It’s a great book. Lots of do-it-yourself projects.