WOW with ROBO
Ages 6–10
Why does pepper move when soap touches water?
Watch ROBO’s pepper-and-soap experiment and explore the surface tension of water.
Why does it happen?
Pepper can float on water. Soap lowers surface tension where it touches the water. The surface moves and carries pepper with it.
Try it yourself
Sprinkle a little pepper on a dish of water. Touch the surface with a cotton swab dipped in dish soap and watch where the pepper moves.
Try with an adult and keep pepper and soap away from your eyes.
