The development of understanding of selected aspects of pressure, heat and evolution in pupils aged between 12 and 16 years

The study is founded on the belief that knowledge based on an individual's prior experience contributes to scientific learning. This is contrasted with a perspective in which it is assumed that concepts have a reality completely independent of the learner. The research is a description of pupils' personal scientific knowledge about several aspects of pressure, heat and evolution. Eighty-four children (aged between 12 and 16 years) were interviewed and asked to give their explanations of scientific problems set in everyday contexts. Categories of response were identified from pupils' words; some of these recurred across different question contexts testing the same scientific concept. They represent frameworks of thought which pupils employ, though they may completely contradict the currently-acceptable scientific notion. Pupil frameworks were identified for the nature of pressure (including a molecular explanation), aspects of fluid pressure, the distinction between heat and temperature, the idea of conduction of heat, aspects of inheritance (including the notion of non-inheritance of acquired characteristics) and for biological adaptation. Their frequencies across three age groups are reported. There was some stability of the frameworks of individual pupils across questions testing the same scientific idea, though the pattern varied from idea to idea. Fifty-eight pupils were re-interviewed after a 20-month interval and the change or stability in thinking of individual pupils was monitored over this period. These results were equivocal. Pupil frameworks relating to some scientific ideas appeared to remain fairly stable overtime, whereas for others pupils drew on different frameworks on the two occasions, frequently on different alternative frameworks. The implications for pedagogy are discussed and it is tentatively suggested that more effective learning might occur if teachers took serious account of pupils' alternative frameworks in their classrooms and laboratories.