My son 's teacher did this fun experiment with his class last week. It's so simple, we were able to replicate it at home. My son poured WHOLE MILK into a plate (whole makes it thicker). Then we added what colors of food coloring we had--yellow and blue). We did several drops of each. Get a cotton swab and dip it in dish soap (one tip of the cotton swab). Now dip that dipped q-tip into the food colored areas and watch the colors spread. Dip it in again and watch the colors repel from the q-tip. Very fun!
Lyndee @ A Recovering Craft Hoarder