“…For instance, international comparative studies have found that opportunity to learn the content on international assessments (such as the Trends in International Math and Science Study) is associated with nation-level performance (e.g., Schmidt et al, 2001) and with differences in performance across U.S. states (Schmidt et al, 2011). At the classroom level, numerous studies have indicated associations of OTL variables with student performance (e.g., Cueto, Ramirez, & Leon, 2006;D'Agostino, Welsh, & Corson, 2007;Ruiz-Primo, Shavelson, Hamilton, & Klein, 2002). In some cases, the effects of OTL are so large that there is no statistically significant residual between-course level (e.g., between general and honors levels) variation in achievement gains after controlling for OTL (e.g., Gamoran et al, 1997;Yoon & Resnick, 1998).…”