The What Works Clearinghouse (WWC) Standards Briefs explain the rules the WWC uses to evaluate the quality of studies for practitioners, researchers, and policymakers. Attrition (loss of sample) occurs when individuals initially included in a study are not included in the final study analysis. Attrition is a common issue in education research and…

This study attempted to implement and validate a 5-month effort to transition 42 pupils with mild and moderate disabilities (most with learning disabilities) out of math instruction in special education resource rooms and into regular education math. A preliminary discussion examines the "cascade of services" model and transenvironmental…