This article presents a curricular reasoning model developed based on research conducted with middle grades teachers as they planned, taught, and reflected on a geometric transformations unit. Teachers can use the model to become aware of their own curricular reasoning to make key mathematical decisions as they plan and teach their lessons. While the data is from middle school mathematics teachers, the curricular reasoning model can be adapted to any grade level. Two video excerpts are included from an elementary mathematics coach/teacher and a high school teacher on how they saw the curricular reasoning model useful across different grade levels, and dataset examples that represent teachers' reasoning about mathematical decisions that impacted the preparation and teaching of their mathematics lessons is shared.