“…For example, some researchers examine the teachers' mathematical knowledge (e.g., Hill, Rowan, & Ball, 2005), or how teachers implement reform-based mathematics tasks (e.g., Henningsen & Stein, 1997). Some analyses from the larger Scaling Up SimCalc study collected data and built on these frameworks (e.g., Roschelle et al, 2010;Sechtman, Roschelle, Haertel, & Knudsen, 2010). For this paper we focus on how three teachers set up and taught the same lesson to meet the needs of their students.…”