ABSTRACT
THE SOLID STATE Several researchers have investigated pupils' ideas about solids. 1 23 For example, Stavy and Stachel1 studied the developing ideas about solid materials held by Israeli children aged 5-13. Their research indicates that younger children tend to regard any rigid material as a solid, any powder as a liquid and any non-rigid material (for example, plasticine, sponge and cloth) as intermediate between a solid and a liquid. Pupils explained that powders are liquids because they 'can be poured' and that non-rigid materials are neither solid nor liquid because they are 'soft' or 'crumble' or 'can be torn'. Thus children decided the state of a material according to its appearance and behaviour with the result that they associated solidity with hardness, strength and non-malleability.
