Students’ conceptions of 1 mol and educators’ conceptions of how they teach ‘the mole’

Abstract

Thirty chemistry students and 28 chemistry educators were interviewed, using a revised clinical method, while they solved a task aimed at revealing their conceptions of ‘the mole’. The educators were also asked how they teach ‘the mole’. Transcripts of the interviews were subjected to qualitative analysis. Students' conceptions of the mole' were described by means of a collective set of conceptions, in which concepts and relations between concepts mentioned by students were represented diagrammatically. A similar set of conceptions was found for the educators. Students expressed conceptions of 1 mol that differ markedly from the conception expressed in the 1971 SI definition of 1 mol. They also had difficulty in relating ‘the mole’ to relevant concepts in a clear and consistent way. When educators solved the task, they used much more ‘professional’ problem‐solving strategies. But ambiguities concerning ‘the mole’ and its relations were also found among the educators. It was possible to describe the educators' conceptions of how they teach ‘the mole’ by means of a collective ‘teaching model’ consisting of five different sets of conceptions, in which the first set is of general character and largely determines the educators' teaching approaches, described by the remaining four sets of conceptions.

The majority of educators were found to teach ‘the mole’ and its relations by means of reasoning methods. Equations were only rarely mentioned. The educator's own conception of ‘the mole’ was found to be a decisive factor when choosing the teaching approach. Although a number of educators gave very ‘professional’ accounts of teaching, they expressed ambiguities, which were found to arise from the overlap of qualitatively different conceptions of 1 mol (described in a previous paper in this journal, Stromdahl et al. 1994). Logical contradictions arise when educators who introduce ‘the mole’ as a number or as a mass by means of reasoning methods later begin to formalize relations mathematically. Certain relations were absent in the accounts of teaching, and these were the same relations which caused the students most problems when attempting to solve the task.