Abstract
In this paper we describe a framework for identifying and classifying students' alternative conceptions and unscientific patterns of reasoning within a particular scientific domain. The framework provides a basic system for indicating how much researchers know about students' non-scientific conceptions and reasoning. Classification at level 1 indicates that students' alternative conceptions or unscientific reasoning were unanticipated by the researchers, at level 2 means the researchers suspected them, at level 3 means they have been partially established (in limited contexts) and at level 4 means they have been established in numerous contexts. The use of the framework is illustrated in identifying student difficulties in biochemistry, in which little such research has been reported. We then suggest how the framework may prove useful, not only for systematically exploring student difficulties in new content areas but also for synthesizing existing research in domains in which a variety of researchers have worked.