Refraction is the name given to the bending of light, as it passes from one medium to another. The most popular example is how swimming pools look shallower than they actually are.

Light bends in different amounts, in different mediums. ie. light will travel faster in water than it will in Pure alcohol.

It's blue-peter time now. What follows is instructions for an experiment you can carry out to find out how light bends through different materials.