Playing with water is always a huge hit in our house. In the summer I set up a water table in the backyard that's used a lot. In the winter water play takes place in the bath tub or sometimes I set up a bin of water. The other day the boys were a little stir crazy and I pulled out our bin and added some water then we tried out a few different ideas.
I saw the idea for playing with balloons and color filled water balloons on Play at Home Mom. I filled a few balloons with air and a few with colored water- I put a drop of food color in the balloon then added the water. I gave the boys scissors so they could cut open the balloons, Next time I will do this outside or in the bathtub because the balloons squirt! They loved seeing what color would come out of the balloon. I used blue and yellow so we could have some color mixing practice.