Wade Chapman.. Age 8, Of Duncanville, Tex., for his question:

What makes water evaporate?

When liquid water evaporates, it turns into vapor and mingles with the other invisible gases of the air. The liquid and the vapor are both made from water particles, and these particles do not change when water evaporates and becomes a gas.

The particles in liquid water cling close together. They have enough energy to slither and slide around, but not enough to separate from each other. In the warm air, the particles at the top of the water get enough energy to free themselves. Off they sail as free floating particles of vapor, and drop by drop the liquid water evaporates and disappears.