This is such a simple activity. You don’t have to buy anything new! All you need are two bowls and a sponge. We used a little one, but a bigger one might work better because more water can be transferred at once.
He is strengthening his hand muscles and also concentrating on keeping the water in the bowls.
He was very excited. He loves anything to do with water.
By the end (after about two minutes of concentration, which I was proud of), he decided to just pour it from one bowl to another, which is very clever, and is practicing another skill — I thought it was sweet that he thought to do it faster this way.