“…Although the most appropriate and effective balance of traditional and ambitious mathematics practices is unknown and debated, the mathematics education field calls for greater amounts of ambitious mathematics instruction across K-12 (e.g., NCTM, 2014b; National Governors Association Center for Best Practices, Council of Chief State School Officers (NGA/CCSSO), 2010; National Mathematics Advisory Panel, 2008), and research finds an incorporation of ambitious mathematical practices into teachers' practice is necessary for student improvement, especially during the earlier years of schooling (Barnett, 1995;Chetty et al, 2010;Currie & Thomas, 2000;Kilpatrick et al, 2001). Nonetheless, take-up of ambitious mathematical practices has been modest (e.g., Hiebert et al, 2005;Hill et al, 2018;Kane & Staiger, 2012;Weiss et al, 2003). Though limited in scope, the research base suggests that this take-up may differ based on classroom or school characteristics, such as performance levels of students and demographics of the student population (Boston & Wilhelm, 2017;Desimone & Long, 2010;Smith et al, 2001;Stipek, 2004).…”