In a geometry content course for K–8 teachers, what broad conceptual ideas/topics are essential? We identified five broad topics, and noted that each of them align with one or more of three major themes (goals for the goals).
Note that this is not intended as a curriculum list. Most of these topics would be hard to imagine as separate units in a course. Instead, they are an outline of the types of topics one might address in each part of the curriculum. Also, much of this list would be appropriate in other math content courses for teachers and is not necessarily specific to geometry.