-Milk (Higher fat content works best)
Pour enough milk to cover the bottom of the bowl. Put a few drops of each of the colors in the center of the milk.
Dip on end of the Q-Tip into dish soap, then give the kids their "magic wands" and let them dip their wands in the center of the food coloring. It's important to tell the kids to only dip their wands in the milk and NOT stir.
Then sit and watch the colors spread, swirl, and mix! If the swirling slows down...dip the soapy Q-Tip back in the bowl.
If you want to know more about the science behind this experiment I would recommend reading Steve Spangler's Website.