ABSTRACT
Particle ideas about liquids Children's ideas about liquids are quite different from the science idea that liquids are composed of tiny invisible particles in constant motion which roll over one another. Before instruction children tend to regard liquids as continuous (non-particulate) and static, but Novick and Nussbaum9 found that, even after instruction in the kinetic theory, over 10 per cent of a sample of 13-to 14-year-olds depicted the particles of air as changed to continuous liquid air when sufficiently cooled. These pupils did not appear to apply the particle model to liquids. Dow et al.,s investigating the particle ideas of liquids held by secondary school pupils, found that children's misconceptions arose mainly from regarding the liquid state as a halfway state between solid and gas. As a result, pupils held ideas that greatly over-estimated the spacing and speed of the particles of a liquid. Often their idea of random motion did not include speed, but only direction. Further, they expected the molecules to slow down over time. These researchers uggest that a liquid based on the pupils' particulate conceptions of a liquid would not have a fixed volume. The molecules would just move apart from each other. The liquid would also be compressible. Moreover, the pupil's model would not allow explanation of the process of evaporation.
