Put the large container in a place where only one end will be warm. For a heat source, you could use a light, a heater, or sunlight shining through a window. Allow this to stand until you see water droplets. This process is called condensation. Water evaporates from the oceans, land, lakes, and cities into the air.
Erosion is the wearing and carrying away of rock and soil by wind and water.
Give each group a large rock and some sand paper. Have the children sand the rock and see what happens. This illustrates the constant wearing away on the earth. Put the bottle in a freezer and allow the water to freeze. Now, show the class the bottle and take notice of how the bottle cracked.