Over the past 15 years, we have seen an increase in the use of cluster randomized trials (CRTs) to test the efficacy of educational interventions. These studies are often designed with the goal of determining whether a program works, or answering the what works question. Recently, the goals of these studies expanded to include for whom and under…

We present results from a meta-analysis of 95 experimental and quasi-experimental pre-K-12 science, technology, engineering, and mathematics (STEM) professional development and curriculum programs, seeking to understand what content, activities, and formats relate to stronger student outcomes. Across rigorously conducted studies, we found an…

Summarizes evidence for the effects of class-size reduction from experimental and nonexperimental measurements, addresses questions about the robustness of each type of estimate, and suggests hypotheses that could reconcile differences resulting from conflicting evidence. Discusses potential costs and the implications for future research into the…

Presents a synthesis of what is known about Title I schoolwide programs, focusing on characteristics of schools and districts implementing schoolwide programs, programmatic and organizational characteristics of the programs, and evidence of program effectiveness. Cautions in interpreting the evaluation findings are presented, and educational…

The effects of a voluntary summer reading intervention were assessed in a randomized field trial involving 552 students in 10 schools. In this study, fourth-grade children received eight books to read during their summer vacation and were encouraged by their teachers to practice oral reading at home with a family member and to use comprehension…

Bilingual education programs for students who speak little or no English are defended as effective by citing research and evaluation studies. (MH)