A framework is presented for thinking about cognitive factors involved in model construction in the classroom that can help us organize the research problems in this area and the articles in this issue. The framework connects concepts such as: expert consensus model, target model, intermediate models, preconceptions, learning processes, and natural reasoning skills. By connecting and elaborating on these major areas, the articles in this issue have succeeded in moving us another step toward having a theory of conceptual change that can provide guidance to teachers in the form of instructional principles. Taken together, the articles remind us that individual cognition, while not the only factor in learning, is a central determining feature of learning. However, we must work to further develop the present partial theory of conceptual change to fill in the missing cognitive core of the present shell.