Water and elements like carbon and nitrogen are constantly being recycled through the environment. This process is called a biogeochemical cycle because it involves both the living organisms and nonliving things in the ecosystem. Three important biogeochemical cycles are the water cycle, carbon cycle, and nitrogen cycle. Learn more about the water cycle in this learning module produced by CK-12.

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In a class demonstration, students observe a simple water cycle model to better understand its role in pollutant transport. This activity shows one way in which pollution is affected by the water cycle; it simulates a point source of pollution in a lake and the resulting environmental consequences.

Students apply their understanding of the natural water cycle and the urban "stormwater" water cycle, as well as the processes involved in both cycles to hypothesize how the flow of water is affected by altering precipitation. Student groups consider different precipitation scenarios based on both intensity and duration. Once hypotheses and specific experimental steps are developed, students use both a natural water cycle model and an urban water cycle model to test their hypotheses. To conclude, students explain their results, tapping their knowledge of both cycles and the importance of using models to predict water flow in civil and environmental engineering designs. The natural water cycle model is made in advance by the teacher, using simple supplies; a minor adjustment to the model easily turns it into the urban water cycle model.

Through an overview of the components of the hydrologic cycle and the important roles they play in the design of engineered systems, students' awareness of the world's limited fresh water resources is heightened. The hydrologic cycle affects everyone and is the single most critical component to life on Earth. Students examine in detail the water cycle components and phase transitions, and then learn how water moves through the human-made urban environment. This urban "stormwater" water cycle is influenced by the pervasive existence of impervious surfaces that limit the amount of infiltration, resulting in high levels of stormwater runoff, limited groundwater replenishment and reduced groundwater flow. Students show their understanding of the process by writing a description of the path of a water droplet through the urban water cycle, from the droplet's point of view. The lesson lays the groundwork for rest of the unit, so students can begin to think about what they might do to modify the urban "stormwater" water cycle so that it functions more like the natural water cycle. A PowerPoint® presentation and handout are provided.

Students learn about the techniques engineers have developed for changing ocean water into drinking water, including thermal and membrane desalination. They begin by reviewing the components of the natural water cycle. They see how filters, evaporation and/or condensation can be components of engineering desalination processes. They learn how processes can be viewed as systems, with unique objects, inputs, components and outputs, and sketch their own system diagrams to describe their own desalination plant designs.

Definition of a change of state and the physical processes that cause it.

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This article explains how the ice and snow of the polar regions fit in the global water cycle and includes links to professional development resources.

ZOOM cast members use a homemade solar still to mimic the water cycle, separating pure water from a saltwater mixture. [3:34]

Groundwater is one of the largest sources of drinking water, so environmental engineers need to understand groundwater flow in order to tap into this important resource. Environmental engineers also study groundwater to predict where pollution from the surface may end up. In this lesson, students will learn how water flows through the ground, what an aquifer is and what soil properties are used to predict groundwater flow.

Animation and text explain the water--or hydrologic--cycle, which is the process that water undergoes in nature.

Water is the source of life on earth. It exists in many forms and is constantly changing. The circulation and conservation of earth's water is called the hydrologic (or water) cycle. Find out how water evaporates, condensates, precipitates, transpires, and is transported around the earth.

This animation from NASA visualizes the steps of the water cycle, including precipitation, evaporation, transpiration, and condensation. [0:52]

Students use a thermal process approach to design, build and test a small-scale desalination plant that is capable of significantly removing the salt content from a saltwater solution. Students use a saltwater circuit to test the efficiency of their model desalination plant and learn how the water cycle is the basis for the thermal processes that drive their desalination plant.

Learn about the four phases of the water cycle, the ways in which watersheds are crucial to healthy water, and the best ways to manage local watersheds with this interactive lesson.

Students learn about the Earth's water cycle, especially about evaporation. Once a dam is constructed, its reservoir becomes a part of the region's natural hydrologic cycle by receiving precipitation, storing runoff water and evaporating water. Although almost impossible to see, and not as familiar to most people as precipitation, evaporation plays a critical role in the hydrologic cycle, and is especially of interest to engineers designing new dams and reservoirs, such as those that Splash Engineering is designing for Thirsty County.

Learn about the different stages of the Earth's water cycle, and about processes involving water, including runoff, infiltration, and the differences between hard and soft water.