Classically, geometry has been the subject in which students encounter mathematical proof based on formal deduction. Attention to proof in the geometry curriculum is strengthened by a focus on reasoning and sense making.

The authors examine the four key elements (conjecturing about geometric objects, construction and evaluation of geometric arguments, multiple geometric approaches, and geometric connections and modeling) identified in Focus in High School Mathematics: Reasoning and Sense Making in more detail and elaborates on the associated reasoning habits.

This volume is one of a series of books that support NCTM’s Focus in High School Mathematics: Reasoning and Sense Making by providing additional guidance for making reasoning and sense making part of the mathematics experiences of all high school students every day.