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I saw a video of this experiment on youtube yesterday and it seemed so simple that I had to try it out myself! The only ingredients are milk, food coloring, and soap.

1. Place milk in a bowl and let settle until all of the bubbles disappear.
2. Add a few drops of various colors of food coloring to the center of the milk.
3. Dip a Q-tip into some dish soap.
4. Touch the surface of the milk and food coloring with the soap-coated Q-tip.
5. Watch what happens!

When you put the food coloring on the milk, the drops remain stationary because the food coloring is less dense than milk and just floats ont he surface.

Then, liquids like milk and water have a cool property called surface tension, which pulls all of the molecules towards the center of the liquid. The drop of soap reduces the surface tension at the center of the milk and so the surface tension is greater outside of the food coloring. At the instant the soap is added to the milk, food coloring moves with the changing surface tension.