We also did an experiment to show that water evaporates. I put water in a clear cup, drew a line where the water level was and wrote the date. We checked the cup 5 days and 10 days later. The kids were amazed that the water level lowered. I was asked how the water vapor got up in the sky since it was in the classroom. I said "it turned into water vapor in the classroom, then when the door was opened it went out into the hallway, then eventually when someone opened the door to go outside the vapor went up into the sky." ... not sure if that is how you explain something like that but they seemed to understand :)
~Ms. Anglin