Results of the last thirty years in mathematics education have shown the importance of an operational concept development. One of the geometrical concepts that has been researched for years already, however, not with the particular focus on its systematic teaching in school mathematics, is the concept of angle. In this paper we focus on children's…

Student conceptions related with matter and the particulate nature of matter (PNM), are vital for advanced understanding in chemistry, and have been a research area of significant attention. Lacking in the literature are studies addressing chemical misconceptions from an ontological point of view. The purpose of the current study was to develop a…