This quasi-experimental and pre/posttest study was designed to examine whether fourth-grade students who engaged in collaboratively writing letters to 11th-grade students performed better on tests of conceptual understanding of a unit on force and motion than students who did not. The participants included 835 fourth-grade students and 416…

Robotics competitions for K-12 students are popular, but are students really learning and improving their STEM scores through robotics competitions? If not, why not? If they are, how much more effective is learning through competitions than traditional classes? Is there room for improvement? What is the best robotics competition model to maximize…

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.…