A few more ideas:Rulers to measure depth of water in various interestingly different containers. Numbered boats with small world people- match number of occupants to boat number.Nets with numbers taped to handles, can you catch that many fish? Sponges-how many squeezes do you need to 'empty' the sponge (this could be a game with scoring, but would need supervision)How many spoonfuls/cupfuls/ sponge squeezes etc are needed to fill a larger container?Fill the water tray with cubes or balls and see how many are needed to fill various containers With cubes in water tray and various flattish trays, measure the dimensions in cubes or find out how many cubes are needed to fill trays.Underwater number ordering- stones with numbers written in nail varnish- place them in order - try doing it hands free using sticks, spoons etc. Unfortunately, all the activities I can think of would probably need some modelling and supervision. I don't think the water tray lends itself naturally to counting activities in the same way as it does to KUW and capacity activities. But I hope these ideas help.