Soap and Detergent
Investigate how food coloring moves in milk when you add a little detergent.
Add detergent to drops of food coloring in glue to make amazing designs.
See how adding a substance to soapy water can change its bubbling ability.
Add a little detergent to the back of a boat and watch it go.
Make different bubble solutions to see which one makes the longest-lasting bubbles.
See if water or detergent solution is better at cleaning lipstick.
Oil and water normally don't mix. See if there is something that can make them come together.
Test different solutions to see which one makes more bubbles.
See what happens to water's surface tension when you add a little detergent to the water.