Twenty studies of the effects of teacher questions on student achievement were reviewed. Internal validity of experiments and integrity of treatments were less adequate than population and ecological validity. Whether teachers used predominantly higher cognitive or predominantly fact questions was found to make little difference in achievement.…

According to the ACT theory of skill acquisition, cognitive skills are encoded by a set of productions, which are organized according to a hierarchical goal structure. People solve problems in new domains by applying weak problem-solving procedures to declarative knowledge they have about this domain. From these initial problem solutions,…