CHEMISTRY TEACHERS’ UNDERSTANDING OF REACTION RATE MODELS: SELECTION, PREREQUISITE CONDITIONS, AND USE

Teachers’ understanding of scientific models is essential for supporting meaningful learning of chemical reaction rates. Yet little is known about how teachers coordinate different dimensions of model understanding in this context. This study examined chemistry teachers’ epistemic understanding of models related to reaction rates, focusing on model selection, prerequisite conditions, and model use. A mixed-methods explanatory sequential design was employed. Open-ended questionnaire items were administered to 52 in-service chemistry teachers, followed by interviews with 10 teachers to elaborate on quantitative trends. The results showed limited understanding across all three dimensions. Many teachers treated the collision model as a literal depiction rather than one representational choice among alternatives. Teachers frequently applied the half-life concept as a universal rule without recognizing assumptions such as constant volume. When interpreting concentration dependence, most relied on simplified textbook patterns rather than using rate laws as representational models grounded in reaction mechanisms. These findings indicate the need for teacher education that explicitly addresses model selection, underlying assumptions, and the functional use of models in reaction-rate instruction. This study contributes a three-dimensional analytical framework for examining teachers’ model-based reasoning and provides a foundation for future research and professional development. Keywords: scientific models, reaction rates, selection of models, prerequisite conditions, use of models