There's a show on TV called Backyard Science that the kids and us enjoy very much. It's an educational show thats presents all kinds of science experiments that kids can do. One recent episode showed how oil and water do not mix and an experiment that shows how.
Because it was another cold and rainy winter day, the kids and their mom decided do the their own version of the experiment. The experiment involved putting oil and water together in a jug and dropping food dye on it. The dye would go through the oil at the top and mix with the water below instead. The results looked gorgeous.