Proportional reasoning is an important but challenging skill for students and teachers. This article, presents findings from two studies investigating whether four categories of reasoning identified by Copur-Gencturk et al. (2022, A Closer Look at Teachers’ Proportional Reasoning. International Journal of Science and Mathematics Education, 21(1), 113–129) apply to a national sample of U.S. middle school mathematics teachers (N = 1,320) and can be captured consistently by similar tasks. We explored the meaningfulness of these reasoning categories with a new sample of middle school mathematics teachers (N = 224) investigating the role of reasoning categories in teachers’ content and pedagogical content knowledge. Both studies suggest that teachers’ proportional reasoning could be grouped into four categories: incorrect, additive, relative, and proportional. Additionally, the way teachers reason in novel proportional situations provides insights into their overall understanding of the content and their pedagogical content knowledge of ratios and proportional relationships.
Copur-Gencturk, Y. & Ezaki, J. (2025). Middle school mathematics teachers’ proportional reasoning and its relation to their content and pedagogical content knowledge. Research in Mathematics Education, 1–21. https://doi.org/10.1080/14794802.2025.2462930