A longitudinal study showing how students use a molecule concept when explaining everyday situations

Abstract

In this paper we present results from a 10 year (1997-2006) longitudinal study in which we, by interviews once or twice every year, followed how students, throughout the compulsory school, developed their understanding of three situations in which transformations of matter occur. We believe that students have to meet scientific ideas early in order to gradually, in social cooperation with classmates, friends, teachers, and other grown-ups, elaborate the meaning of a concept. We followed 23 students all born in 1990. 1997 we introduced the idea of the particulate nature of matter. We have conducted interviews allowing students to explain the transformation of matter in fading leaves left lying on the ground, burning candles, and a glass of water with a lid on. In the interview at 16 years of age less than one fifth of the students use molecular ideas in scientifically acceptable ways. The overall conclusion is that most students do not connect the knowledge they gain in school about the particulate nature of matter to these everyday situations. On the other hand the students seem capable of using a simple particle model and the model can help them understand the invisible gas state. The question of how to use this capability in order to develop students’ scientific ideas is still not solved and more research is argued for.