As a learning tool, argument and decision maps enable students to hone their interpretive and analytical skills. This paper illustrates one effective approach to teaching the diagrammat­ic conventions used in a powerful decision and argument mapping methodology. The twenty example maps included begin with a configuration illustrating one reason offered in support of a conclusion, and build to highly complex maps illustrating the analyses of real world decisions as recorded in interviews and official documents. Using their interpretive and analytical skills, (...) and the simple conventions taught and illustrated here, students and researchers are able to build and to refine maps that show simple arguments, lines of reasoning, unspoken but implicit as­sumptions, pro and con argumentation, individual and group decision making, the influences of reactive cognitive heuristics on decision making, the use of various familiar valid and fallacious inference patterns, and the bolstering phenomenon associated with the use of multiple arguments in support of a given option. (shrink)