This paper examines how controlling statistically for baseline covariates (especially pretests) improves the precision of studies that randomize schools to measure the impacts of educational interventions on student achievement. Part I of the paper introduces the concepts, issues, and options involved. Parts II and III present empirical findings…

There is now ample evidence that teachers tend to make substantial modifications to both the prescribed content and methods of the curricula they administer, and that such modifications are likely to attenuate curricula effects. We examine the fidelity with which teachers implement "Protecting You, Protecting Me," an underage alcohol use…