I can't get my kids to stop BEGGING to play this game!!! It's VERY simple and a wonderful and engaging Math Center that can easily be differentiated. You will need numbered (on bottom) rubber duckys, some kind of counter manipulative (I use the red/yellow and call them the duck eggs!) and a container of water that your ducks can fit into. The attached worksheet I use to keep track of their progress. Can be done alone or with a partner.