Randomized experiments are often considered the strongest designs to study the impact of educational interventions. Perhaps the most prevalent class of designs used in large scale education experiments is the cluster randomized design in which entire schools are assigned to treatments. In cluster randomized trials (CRTs) that assign schools to…

Less than one third of American eighth graders score in the two highest performance levels on the grade 8 mathematics test given by the National Assessment of Educational Progress. Only a little over one third of Massachusetts eighth graders score at the two highest performance levels on the state's own grade 8 mathematics test. In 2002, the…