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…

Background: Cluster-randomized experiments that assign intact groups such as schools or school districts to treatment conditions are increasingly common in educational research. Such experiments are inherently multilevel designs whose sensitivity (statistical power and precision of estimates) depends on the variance decomposition across levels.…

Math Snacks animations and support materials were developed for use on the web and mobile technologies to teach ratio, proportion, scale factor, and number line concepts using a multi-modal approach. Included in Math Snacks are: Animations which promote the visualization of a concept image; written lessons which provide cognitive complexity for…