State content standards are the backbone of the standards-based reform movement. Content standards provide teachers with a set of guidelines for what students are expected to know and be able to do, defining the intended curriculum. And although the current 50-state system of education gives each state the task of setting content standards, there…

The present meta-analysis examines the effect of grade retention on academic outcomes and investigates systemic sources of variability in effect sizes. Using multilevel modeling (MLM), the authors investigate characteristics of 207 effect sizes across 22 studies published between 1990 and 2007 at two levels: the study (between) and individual…

Research in fields other than education has found that studies with small sample sizes tend to have larger effect sizes than those with large samples. This article examines the relationship between sample size and effect size in education. It analyzes data from 185 studies of elementary and secondary mathematics programs that met the standards of…

The author examined the effects of professional development (PD) on literacy instruction using 75,689 lessons from 1,945 classrooms in 112 schools participating in the Study of Instructional Improvement. Stratifying over 94 pretreatment covariates, including prior instruction, the results revealed the importance of PD as a lever for changing…