What Is the Water Cycle?
Encourage students to suggest variations of the investigation. For example, food coloring can be used to model pollutants. Add a few drops of several colors on or into the sand. Place the ice cubes on top of the sand, cover the box and place it in a sunny location. Have students observe the colors leaching into the “lake” and dissolving into the water, that were in the water are left behind.
Additional variations of the model might include covering the box with different material or changing the contour of the sand.
Students also can investigate how water behaves by observing ice in a sealed plastic bag placed in a sunny window. Specifically, students should be able to observe evaporation and condensation. To demonstrate what would happen if the water cycle was not a closed system within Earth’s atmosphere, use a bag that is perforated or has several holes. This will permit some water vapor to escape and minimize the amount of condensation in the bag. Over time, most of the water in this bag will leave by evaporation and the movement of gas molecules.
- Moreno N., and B. Tharp. (2011). The Science of Water Teacher’s Guide. Third edition. Baylor College of Medicine. ISBN: 978-1-888997-61-3.
- National Science Foundation. (2005). The Chemistry of Water.
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Funded by the following grant(s)
The Environment as a Context for Opportunities in Schools
Grant Numbers: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education