Learning and Teaching about Matter in Grades K–8: When Should the Atomic-Molecular Theory be Introduced?

The atomic-molecular theory is one of the most important scientifi c theories, on par with Darwin’s theory of evolution. It is important that it be familiar to students graduating from high school but, like evolution theory, it is highly counterintuitive for most students, and current K-12 science teaching is typically not effective in helping them understand and accept it. Rather, the majority of high school and even college students (including chemistry majors) have many fundamental misconceptions about atoms and molecules, and many fail to understand the central tenets of the theory, as well as its explanatory power.