Fifth graders should learn the terminology used when investigating how water cycles work, including words such as precipitation, evaporation and condensation. They also should be taught the sun's role in water evaporation -- for example, how it heats the water into vapor, which then goes up into the air. Teachers should discuss where this evaporated water actually goes (into the clouds) and why it rises into the atmosphere (because water vapor is lighter than air).
The Internet contains numerous interactive websites designed to teach kids about water cycles, including a website from the United States Environmental Protection Agency (see Resources). This web resource uses interactive child-friendly graphics that illustrate how the water cycle occurs. Let the kids navigate through the graphics to learn more about water cycles.
The concept of evaporation is the cornerstone of understanding how the water cycle works. To illustrate this concept, let each student put one teaspoon of water into an open container and let it stay there until the water evaporates. This way your fifth graders can see with their own eyes how evaporation occurs.
No lesson about water cycles would be complete without covering why water resources are important. Tell the students that fresh water reservoirs are limited to rivers, lakes, underground water and glaciers. Mention that most of the water on the planet is mixed with salt and can be found in oceans and seas. To highlight why fresh, clean water is important, ask the students to come up with examples of ways they use water in their everyday lives. Sum up your lesson with the message that pollution and overuse of water resources deprives future generations of clean water.