“…Fourth, the question of how to impact the instruction of a large number of teachers further complicates the issue (e.g., Maass & Artigue, 2013;Roesken-Winter, Hoyles, & Blömeke, 2015). So far, little is known on how to scale up professional development (Jackson et al, 2015;Roesken-Winter, Schüler, Stahnke, & Blömeke, 2015).…”