Children's understanding of changes of state involving the gas state, Part 2: Evaporation and condensation below boiling point

Deriving from a three‐year longitudinal study which explored the development of children's concept of a substance (ages 11 to 14), part 2 of this paper (see Johnson 1998b) reports findings in relation to evaporation at room temperature and condensation of atmospheric water vapour. Part one had reported findings in relation to boiling water and the development of pupils’ understanding of particle ideas. The correlation between responses to all of the phenomena is examined. There was a high consistency amongst them, and an understanding of the nature of the gas state was found to be the underlying issue, with the particle theory playing a key role. Some claims in the literature of children's understandings are challenged and the adequacy of the teaching of introductory particle theory is questioned.