Jed Lipinski: In the fall of 1971, Bill Heinemann and Paul Dillenberger returned to their Crystal, Minn., apartment to find their roommate, Don Rawitsch, sprawled on the living room floor, drawing a map of western America. The three men, all seniors at Carleton College, were student teachers. They spent their days in junior high classrooms teaching math and history in inner-city Minneapolis. At night, they huddled over dinner, sharing tips and debating teaching techniques. Until earlier that day, Rawitsch had been stumped on how to get his eighth-graders interested in his new history unit, “The Western Expansion of the Mid-19th Century.