Send molecules flying with this super fun and easy science experiment for kids (and adults): The Soap Boat Water Experiment from The Royal Institution’s ExpeRimental series. Comedian Rufus Hound and his son Alby make soap powered boats — there’s a pdf template and more useful info here — by breaking the surface tension of the water behind the boats. Watch as they start the video with a “super powers” demonstration.
Rufus and Alby do a science magic trick with some pepper (or oregano, if that’s your flavour), washing up liquid and water. Watch the flakes shoot across the water at the touch of a finger. They experiment with different liquids, investigating how substances around the house affect the surface of water. The dramatic effect you see is because the soap weakens the pull that water molecules have on each other. As a result, as the soap spreads over the surface of the water, the water is able to pull away, taking the oregano or pepper with it.
We love this classic experiment because it’s so easy, and the reaction is pretty impressive, even after doing it over and over again.