Homework is a common instructional practice that is used to motivate students, develop students' studying skills and habits, inform parents about student learning, and increase student achievement. Homework provides an opportunity for students to revisit daily topics, and improve students' understanding of math concepts and problem-solving skills,…

In educational effectiveness research, it frequently has proven difficult to make credible inferences about cause and effect relations. The article first identifies the main categories of threats to valid causal inference from observational data, and discusses designs and analytic approaches which protect against them. With the use of data from 22…