1. Get a shallow plate and fill it with milk.
2. Put a few drops of food colouring in different spots around the milk. You can use as many colours as you like!
3. Now grab your clean cotton tip and dip it in the milk, pull it out and poke it into some dishwashing detergent.
4. Finally, put your cotton tip back into your plate of milk and watch as the food colouring goes crazy!
5. If you like, give the milk a stir to see more colour movement.

The reason for the changing colours is that the detergent works to separate the food colouring from the milk. The dishwashing detergent breaks up the molecules and makes them zing around your plate. Cool!