Children's understanding of substances, Part 2: Explaining chemical change

Abstract

This is the second part of a paper which focuses on the idea of chemical change (see Johnson 2000). The reported data comes from a study which explored the development of children's concept of a substance (ages 11-14). It examines the use of the ideas of elements, compounds and the bonding between atoms to explain chemical change and the intersection of these ideas with 'basic' particle ideas. Evidence is presented which suggests that the particle ideas were the means by which the pupils came to acknowledge the phenomenon of chemical change, having been unmoved by a macroscopic approach which identified substances by melting and boiling point. Furthermore, a basic particle model in which individual particles still retained the macroscopic properties of the substance was found to inhibit an understanding of chemical change. Findings with respect to a burning candle are reported in a separate section. Important implications for teaching are discussed.