stephens-2009ecr

As part of a larger investigation into the kinds of reasoning processes experts and students use during model-based learning, this study investigates the use of one such process, extreme case reasoning. We asked whether evidence for the generation and use of extreme cases by experts and by students could be documented from case studies, and if so, whether this might be associated with the use of dynamic mental imagery. To do this we analyzed videotapes of (1) scientifically trained experts and (2) secondary physics classroom discussions. In the episodes presented, there is evidence that: experts can generate creative test cases for extreme case reasoning when engaged in mental modeling and can then use the process to reason about important steps in problem solving; students can generate creative test cases for extreme case reasoning when engaged in mental modeling, and can then used the process to reason about important conceptual issues. There is evidence that experts and students can make use of mental imagery when engaged in extreme case reasoning and that at least some of this imagery is dynamic in nature. We conclude that there is case study evidence that extreme case reasoning can contribute to theory construction in scientists and in students, and that this non-formal reasoning process may involve mental imagery and simulation in a central way.