To support teachers in implementing ambitious reform efforts, professional developers and teacher educators need to know more about teachers' thinking about argumentation. Specifically, there is a need to understand more about teachers' views and evaluations of "students'" mathematical arguments as they play out "in practice."…

To teach the rigorous skills and knowledge students need to succeed in future college-entry courses and workforce training programs, education stakeholders have increasingly called for more rigorous curricula, instruction, and assessments. Identifying the critical attributes of rigor and measuring its appearance in curricular materials is…