Conceptual reorganization and the construction of the chemical reaction concept during secondary education
Aspects of 40 pupils' (aged 12-18) conceptual reorganization and change, related to the construction of the chemical reaction concept were studied. Data were collected with the Free Categorization Task and the Interview About Instances techniques, both involving a clinical interview with each pupil. The dynamic of conceptual change is described through (a) case studies refering to the pupils' categorizations of 19 everyday life physical and chemical phenomena, and collective representations of the semantic categories spontaneously activated by the pupils in order to categorize the 19 phenomena and (b) the pupils' identifications of chemical reactions among the 19 phenomena, and their definitions of the chemical reaction concept. The outcomes show how pupils reorganize their conceptual domain and proceed to the construction of the chemical reaction concept in three distinct stages. A number of misconceptions were revealed, as well as problems with chemistry teaching, concerning the lack of construction of the chemical substance concept. Proposals for the improvement of chemistry teaching are made.