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So simple to assemble and so soothing to play with. Simply fill a jar two-thirds of the way to the top with water. Add a few drops of food coloring. Fill the remaining third of the jar with oil. Shake and observe the bubbles!

Here is a little science: oil is less dense than water, which is why it will float to the top when it settles.

Water molecules are polar: they have a positive charge on one end and a negative charge on the other. They are more attracted to one another (and stick together) than to oil molecules, which are non-polar and have no charge.

You can make oil and water mix together by adding an emulsifier to the mix. You could also experiment with making oil temporarily sink by sprinkling in some salt. The salt will make a ball with the oil and sink down through the water ... Until it dissolves and the oil returns to the top.

Add some additional interest to your jar with some small toys or shells or beads!