Ask children where the rain and clouds come from. Encourage discussion, questioning what happens when we boil water in a kettle and where the vapor goes. To show preschoolers that in nature water evaporates without boiling, distribute small plastic containers or saucers. Every child puts a small quantity of water in the container, marking its level with a pen. Encourage children to place their containers in places that receive different amounts of sunlight. Observe the natural evaporation of water every day.
Collect magazine pictures showing landscapes with water in different forms: liquid, in rivers, lakes, rain, oceans; solid, in frozen lakes, icicles and snow; and vapor, in clouds. Ask children to identify where they see water in each illustration. Encourage discussion, asking if snow and clouds are also made of water. Ask the children to point out the differences between the three forms of water in nature. Bring some ice cubes, boiling water and cold water to class so children can concretely observe the three states of water.
Divide the children into groups of three or four. Distribute a large piece of paper, crayons or paint and old magazines. Ask the children to find and cut illustrations showing water in different states. Encourage them to glue them on the paper, forming separate groups or columns. Alternatively, draw a sketch representing the rain cycle in nature and ask children to color it in or paint it.
You can show children how clouds are formed by making one inside a jar. Pour some boiling water inside a heatproof glass jar. Darken the room and put a metal pie pan with ice cubes on the top of the jar. When you shine a flashlight through the middle of the jar, you can see a cloud forming. Encourage children to create hypotheses about what they see. Explain that in nature, clouds are formed when vapor is cooled.