Identify at least four ways that ecosystems support life (e.g., by providing fresh water, generating oxygen, removing toxic pollutants, and providing sources of useful materials).
In prior grades students learned that all plants and animals live in and depend on habitats. In grades 2-3 students learn that ecosystems include plant and animal populations as well as nonliving resources. Plants and animals depend both on each other and on the nonliving resources in their ecosystem to survive. Ecosystems can change through both natural causes and human activities. These changes might be good or bad for the plants and animals that live in the ecosystem, or have no effect. Humans can protect the health of ecosystems in a number of ways.
Ecosystems support all life on the planet, including human life, by providing food, fresh water, and breathable air.