This environmental education program emphasizes the cause and effect of change in an estuary ecosystem with special attention given to man and his role in environmental change. Concepts are employed from the natural and social sciences to investigate environmental problems. The units are designed around these questions: (1) What is an ecosystem?; (2) What is a description of the ecosystem being investigated?; (3) What are some of the biotic and abiotic features of the ecosystem and how do these features interrelate?; (4) Where are some specific locations of the ecosystem being investigated?; (5) What biotic and abiotic features in the ecosystem have changed and are undergoing change?; (6) What are the natural factors causing change in the ecosystem and how have they been brought about?; (7) What are the man-made factors causing change in the ecosystem and how have they been brought about?; (8) What are the results of the changes?; (9) What, if any, new changes are needed in the ecosystem?; and (10) How might these needed changes to the ecosystem be brought about? The units are inquiry oriented and contain learning activities, resources, evaluation techniques, and teacher suggestions on implementation of the program. Readings, maps, and other handouts are given for learner use. (Author/MR)