Bursts of Energy...
Recommended grade levels: 2-6
Goal: Students will explore the role of the sun in the water cycle.
Process skills: Connections Observing Predicting
Materials: (for whole class demonstration, or per student group) one large glass or clear plastic bowl soil one small glass or bowl (shorter than the large bowl) one heavy object to weigh down glass clear plastic, masking tape or rubber band, water ice cubes or commercial freeze-pack (Blue Ice, Polar Ice, etc. ) heat lamp (optional)Teacher background information:
The water cycle is a continuous process. A very small percentage of all rainfall is taken up and used by plants. The remainder falls in the ocean, drains into rivers and lakes or seeps into the ground. Ground water eventually finds its way into rivers and back to the sea.
When sunlight warms water, some of the water evaporates into the atmosphere. The water vapor is blown about by the wind. The water vapor eventually cools, condenses and falls in droplets like rain.
In this activity, which can be a teacher demonstration or a teacher-led activity for groups of students, the water cycle and the direct use of solar energy will be observed. As the water in the bowl is warmed, some of the water evaporates. The ice cubes provide a cool surface for the evaporated water to condense in droplets. These water droplets collect on the plastic wrap. The ice cubes weigh down the plastic wrap so that the condensed water droplets are "funneled" into the glass. The empty glass will collect the clean water droplets that have formed on the plastic wrap.
Note: If a sunny place is not available, use a heat lamp instead. Many teachers have found this activity works with a 100 wall bulb in a goose neck lamp with a reflector shade (often included in science kits). Using a heat lamp will take longer time than when in direct outdoor sunlight.Procedure: