Interest has rapidly increased in studies that randomly assign classrooms or schools to interventions. When well implemented, such studies eliminate selection bias, providing strong evidence about the impact of the interventions. However, unless expected impacts are large, the number of units to be randomized needs to be quite large to achieve…

Describes statistical analyses of tests used for organic chemistry classes and attempts to pose a model to explain the results. Concluded that students who possess a slight grasp of a concept actually have less of a chance of answering an item correctly than those who merely guess. (CW)

Clues in the answers given to the Spanish Advanced Placement Examination questions can identify the test-taker as having learned the language in the classroom or as a native speaker. The Educational Testing Service has found mechanisms to ensure that the tests are equally suited to the two groups. (MSE)