A Level Engineering Science: a progress report

This paper presents findings from a case study into the development of student understanding of a complex and abstract scientific concept: chemical bonding. The case study reveals significant progression in student understanding, but also highlights issues of how such progression should be addressed. Particular emphasis is given to the factors that were associated with ‘blocks’ to appropriate concept development. The learner discussed had her own ‘alternative conceptions’ of ionic charge and electrostatic attraction that, lacking the appropriate background knowledge, she used in order to make sense of chemistry. These alternative ideas blocked the development of an electrostatic framework for bonding to replace the ‘full outer shell heuristic’ used at the General Certificate of Secondary Education (GCSE) level, and had repercussions for the understanding of a range of related concepts. The importance of diagnosing learners’ alternative ideas is thus demonstrated, and some of the problems of carrying out such diagnoses are considered.