NASA
Water Works on a Blue Planet
Keep within a water budget. Learners find out that less than 2.5% of Earth's water is available to drink—and that there is a fixed amount of water. Scholars read an interesting article comparing the available water to a game of Monopoly...
Open Curriculum
Open Curriculum: Recycling Matter in Ecosystems
Students learn about biogeochemical cycles that recycle matter on Earth.
University of Illinois
University of Illinois Extension: Energy and Ecosystems Use Some Lose Some
Life on Earth is possible because energy flows one way through ecosystems, while matter cycles endlessly. Water and elements, such as carbon, nitrogen, phosphorous, and sulfur are examples of matter that cycles through ecosystems.