Development of conceptual understanding of physical and chemical changes at the macroscopic, submicroscopic and symbolic level: a cross-age study

Abstract

In order to explain the development of understanding of chemical concepts at the macroscopic, submicroscopic and symbolic level over time, models of the expanding triangle and rising iceberg are proposed. In order to validate the two models, this study examined whether the depth of understanding of the concepts physical and chemical changes at each of the levels significantly changes with the age of students, whether selected age groups exhibit significant differences in understanding at the three levels, and whether findings for these age groups differ. Therefore, 121 14-yearold, 108 16-year-old and 112 19-year-old students completed the test that checked their understanding of the aforementioned concepts, at all three levels. The 16- and 19-year-old students significantly outperformed the 14-year-old students at each of the levels, while all age groups showed significantly better understanding of physical and chemical changes at the macroscopic and symbolic, in comparison to the submicroscopic level. It was concluded that, while the proposed models are generally valid, the applied teaching approaches and the composition of the chemistry curriculum have a profound impact on the development of students’ conceptual understanding, at all three levels of chemistry knowledge.