The What Works Clearinghouse (WWC) Standards Briefs explain the rules the WWC uses to evaluate the quality of studies for practitioners, researchers, and policymakers. This brief explains what baseline equivalence is and why it matters. As part of the WWC review process for certain types of studies, reviewers assess whether the intervention group…

Describes a technique to make multistage cluster sampling easier for students to understand. Explains that students handle concrete objects that are analogous to the sampling units of a multistage cluster sampling procedure. Suggests that this method is inexpensive, easily organized, and stimulates the tactile senses in the learning process. (DK)

At Park Senior High School (Cottage Grove, Minnesota), 46 juniors and seniors planted 384 red pine seedlings in connection with their original research on acid rain, with advice from Dr. Harriet Stubbs, director of the Acid Precipitation Awareness Program (West Saint Paul), which has been developing acid rain teaching materials. (MH)