All you do is pour some Vitamin D Milk into a shallow dish. Let the little hands drop some food coloring into the milk. And then add a drop of dish soap and watch it dance.
They loved it so much that we did it twice. I think the one below is Natalie's. And the red one I know is Cohen's. I didn't do a good job of documenting which one belonged to who. Oh well, next time.
Here the two are with their second go at it. They wanted to do it again, but all the food coloring was gone.