The key is that as a change happens in one part of an ecosystem, there is a corresponding response by all the other organisms that are present. In many cases, elements like pesticides are harmful to an ecosystem - although they were originally designed to be beneficial. Introducing them into an ecosystem often sets off a chain reaction of events that devastates the entire system. In the case of industrial pollution like acid rain, the problem is even worse, causing widespread destruction over a large geographic region. Students conduct a simple investigation.
Students employ simple equipment and tools to gather data and extend the senses.
Students use data to construct a reasonable explanation of how an ecosystem works. Students communicate investigations and explanations. Students discover that all animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat plants.