En longitudinell studie av 10-12-åringars förståelse av materiens förändringar

Sammanfattning: The main aim of this study was to study young people’s ability to use science knowledge when talking about and explaining everyday phenomena involving transformations of matter. Pupils’ individual knowledge was studied both through their spontaneous explanations and through their explanations with appropriate help in discussions with me or with other pupils. The framework for learning in this study involved both pupils’ individual learning and their learning in a social context. In the project, pupils discussed everyday phenomena with peers and with me. The role of the discourse was stressed in the interviews as well as pupils’ use of parallel models of explanations. Data were gathered through four interviews with each one of 40 pupils from five classes during a longitudinal study over two years. The pupils were about 10 years old at the first interview. During the study three instructional units were carried out in the five classes. In the first instructional unit a basic particle model was introduced, to be used when discussing experimental situations during the instructional units. The development of the basic particle model was one of the themes during the instructional units. Other recurrent themes were states of matter, gases and chemical reactions. I decided not to introduce the concept of chemical reaction until the last instructional unit. Pupils’ statements in the interviews were categorised from these themes. The categorizations emanated from presented research on pupils’ conceptions of science but also from the statements of the actual group of pupils. The correctness of the science concepts used was also taken into account in the categorizations. Sometimes I altered a method used before and sometimes I developed a categorization for a special purpose in my study. An example of the category systems is the combined classification of pupils’ conceptions of the particle nature of matter that contains three perspectives: A/ the quality of pupils’ particle model as revealed during the interview B/ the nature of pupils’ use of the concept of molecule during the interview C/ the number of situations in the interview where pupils use the concept of molecule. The pupils did not replace their old models; they put for example a new particle model beside their old everyday model. Then they chose which model to use when they met new situations. Most of the pupils were able to use knowledge of science when talking about known everyday phenomena involving transformations of matter. Almost all of the pupils in the group developed their own thinking models during the project. Pupils’ growing ability to describe features of chemical reactions and the development of their own particle model could help them to understand for example the nature of chemical reactions.