The paper is a primer-introduction to understanding graphical models, addressed to students. It is one of a group of draft lesson plans, for use in teacher training. The 16-page paper is an excerpt from an environmental education research project sponsored by the United States Dept. of Education. The project was headquartered at the University of Virginia under direction of J. N. Warfield. Walter Bogan, director of Office of Environmental Education, was the contract supervisor. This material was shipped to Fenwick Library Special Collections, George Mason University, Fairfax, VA on 23 October 2000.
