Abstract
Most chemistry instruction and assessment lie in the symbolic domain of Johnstone's representational levels, despite years of chemistry education researchers calling for increased emphasis to be placed on the molecular or particulate level of chemistry. Without a deep understanding of the particulate nature of matter and molecular-level interactions, meaningful chemistry understanding is nearly impossible. Understanding how molecules and other particles interact provides the necessary explanatory elements for predicting how chemical reactions will occur. To address this gap, the VisChem Approach was developed for university students in Australia in the late 1990s, but it was only recently formally brought to high schools in the United States. In this study, we examine the results of high school teacher implementation of the VisChem Approach in four classrooms following an intensive professional development program. Results indicate that the curricular inserts are successful in addressing many areas of misunderstanding by students regarding the molecular level. Implications for teaching using the VisChem Approach and for research on students' understanding of the molecular level are also discussed.