For this colorful science activity, you'll need to gather clear plastic cups, Liquid Watercolor in various colors, vegetable oil and droppers to use with the Liquid Watercolor. Split the supplies needed by having children work in pairs together.
Provide each child with two cups: one with oil and one with water. Also provide each child with a container or cup of Liquid Watercolor.
Have children place drops of Liquid Watercolor into each cup. They'll discover that the water changes color, but the Liquid Watercolor just floats on top of the oil, which does not change.
Next, have the children place some oil and water into the same cup. They will observe that the oil floats to the top, resting just above the water. Have the child place a few drops of watercolor on the top and observe how the drops just sit on the top.
Children can then "magically" change the color of the water by putting some Liquid Watercolor into a dropper and releasing it underneath the oil. The water will change color while the oil does not.