Educator's guide

National parks and reserves -- Chesapeake Bay Watershed (Md. and Va.) -- Computer-assisted instruction -- Handbooks, manuals, etc. Water quality -- Chesapeake Bay Watershed (Md. and Va.) -- Computer-assisted instruction -- Handbooks, manuals, etc. Chesapeake Bay Watershed (Md. and Va.) -- Environmental conditions -- Computer-assisted instruction -- Handbooks, manuals, etc. Chesapeake Bay (Md. and Va.) -- Environmental conditions -- Computer-assisted instruction -- Handbooks, manuals, etc.