Chemistry Teachers’ Pedagogical Content Knowledge and Belief on Integrating Proportional Reasoning in Teaching Stoichiometry

Proportional reasoning refers not only to the ability to manipulate the proportions, but also to detect, express, analyze, explain, and provide evidence in support of assertions about proportional relationships. Students’ understanding of the proportional relationships that they encounter in science can be improved through well-designed instruction. In other words, teacher practice is key to the successful learning of both proportional reasoning and science. Stoichiometry is a basic topic in chemistry that focuses on the proportional relationship between the amount of reactants and/or that of products in a chemical reaction. This study explored 10 chemistry teachers’ knowledge and beliefs on integrating proportional reasoning in teaching stoichiometry mainly through interview, survey, and lesson materials. The framework of pedagogical content knowledge was used to examine key dimensions of teacher knowledge that were triggered as they teach stoichiometry. Moreover, teachers’ problem-solving strategies were sorted by using the proportional reasoning strategies framework. Three representative case studies allowed a deep analysis and the relation of each component of pedagogical content knowledge with implications for teacher education and professional development design.