A, Bee, C, Preschool: Building Shapes. Kindergarten readiness: Colored craft sticks are labeled with the number of sides each shape has, ie: 3 purple sticks - triangle. The children will choose a color and build the matching colored shape from the sticks.
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).