This activity jumped out at me at the Dollar Store. It is a first aid band meant to get cold in the fridge and then strapped to the wrist to relieve pain. I immediately loved the feel when squeezing one end and watching the contents squish over to the other end. this is great for strengthening fingers, especially the index, middle fingers and thumb used to grasp a pencil. My very young hippotherapy clients found it fun and some loved it so much.
I was able to use it to reinforce (read- bribe) some of them to engage in tasks they normally don't do willingly- such as lie on the belly in prone extension.