As a liquid heats up, its molecules collide into one another, causing them to take up more space. Some of these molecules have enough energy to change into a gaseous molecule.
But when happens as these gaseous molecules begin to cool down?
Sixth graders are looking at the process of condensation. They've developed a model to explain this phenomenon.
We've also looked at real world examples of this process--"fog" on the mirror in the bathroom after a cold shower, contrails behind a jet flying in the sky, water dripping from a glass filled with ice water.