I love this activity because you can do so much with it! All you need is Chalk, and Foam Blocks. I simply wrote some numbers on the ground with different color chalk and covered it with different shapes. Then I poured some of the foam blocks out and let my daughter have at it.
I had my daughter match the foam block colors to the chalk colors.
I had my daughter match the foam block shapes with chalk shapes.
I had my daugher color match and count the foam blocks with the chalk.