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 describes English language learner (ELL) student enrollment and achievement trends in Delaware public schools from 2002/03 to 2008/09. Two research questions guide this study: (1) How did the enrollment of ELL students in Delaware public schools change between 2002/03 and 2008/09?; and (2) How did performance (the percentage scoring at…

This study describes English language learner (ELL) student enrollment and achievement trends in Delaware public schools from 2002/03 to 2008/09. Two research questions guide this study: (1) How did the enrollment of ELL students in Delaware public schools change between 2002/03 and 2008/09?; and (2) How did performance (the percentage scoring at…

There is continuing controversy about the optimal or appropriate age at which children should start school. The purpose of this study is to examine the relationship between age and achievement. It is an attempt to evaluate the hypothesis that older students fare better academically than their younger classmates. Findings indicate that on average…