Provide the children with the definition of ecosystems. Essentially, an ecosystem is a collection of organisms and nonliving elements, such as soil, that live or are located in a particular environment. The examples of ecosystems include a rainforest, with all its fauna and flora, coral reef, desert, prairie, tundra and taiga.
Provide information to third graders about the interdependence and fragility of ecosystems. The elements of an ecosystem are typically very interdependent. In the ecosystem of a rainforest, many animals are dependent on the trees. At the same time, the trees may be dependent on some animals, such as birds to kill the insects that may damage the trees. If an element of an ecosystem is damaged, for instance, trees of the rainforest are cut down by humans, many organisms that live there can perish.
People also live in an ecosystem, though humans are more adaptable than rainforest apes or rare fish species of the coral reef. The ecosystem that humans depend on includes the sun, air (oxygen), fresh water and soil. Some people forget about the importance of the human ecosystem to the survival of humans, and damage the air and water that people depend on by contaminating it with pollutants
Tell the children about the pollution of ecosystems. Pollution is a major issue in ecosystems. Each year, many thousands of tons of toxic chemicals are dumped into the water, air, soil. To prevent pollution, people in different countries need to introduce measures to curb emissions of harmful chemicals. In the United States, the ecosystems and the environment are protected by many laws. The Environmental Protection Agency, or EPA, is a leading federal agency that looks after ecosystems.