This little puzzle is a nice way to close a lesson on density, buoyancy and Archimedes' principle: Let students conduct the experiment in class and look for an explanation at home.

A simple yet memorable way to teach fractions with 3 cups and a bit of water.

Surface tension can hold a surprising volume of water on a coin. If the surface tension is reduced, e.g. by adding a surfactant, the water spills over at a far lower volume.

Capillary forces in a wick can transfer oil to a flame or a liquid from one vessel to another. But what makes a good wick? Let your students find out in a small competition.