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.…

This study examines the relationships between student literacy performance and discussion-based approaches to the development of understanding in 64 middle and high school English classrooms. A series of hierarchical linear models indicated that discussion-based approaches were significantly related to spring performance, controlling for fall…