Children's understanding of substances,part 1: recognizing chemical change |
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Authors: | Philip Johnson |
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Institution: | School of Education, University of Durham, Leazes Road, Durham, DH1 1TA, UK |
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Abstract: | Arising from a study which explored the development children's concept of a substance (ages 11-14), this two-part paper focuses on the idea of chemical change. Part one considers substance identity and pupils' interaction with the scientific idea of melting and boiling behaviour as a means for identification and the assessment of purity. Evidence is presented which suggests that children do not 'naturally' have a concept of substance identity which allows them to recognize chemical change as a possibility. Instead, their thinking is in terms of the history of samples. The scientific idea of identity led to a confrontation with the idea of chemical change but the pupils were unwilling to accept this phenomenon. The preference was to view the product of a chemical change as a 'mix' of the original substances rather than as a substance in its own right. Implications for teaching are discussed. Part two (in press) goes on to examine the issue of explaining chemical change. |
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