ABSTRACT
CHEMICAL CHANGE Although in science the term 'chemical change' is reserved for processes in which the reacting chemical substances disappear and other (new) substances appear, several studies have found that children often use the term 'chemical change' to encompass changes in physical state and other physical transformations, particularly so when the colour of a substance alters.3 5 6
Some educators do not distinguish between physical and chemical changes on theoretical grounds but others find such a distinction useful for the development of science ideas.7 8 9 How well pupils make such a distinction depends partly on their conception of 'substance'. For instance, if they regard ice as a different substance from water, then they are likely to classify the melting of ice as a chemical change. VogelezanglO has suggested that substances should be regarded as identical if their properties are identical when compared under the same conditions.
