Authors of the taxonomy made various claims about its properties that concern both educational and psychological issues; these claims have stimulated investigations of the taxonomy's validity. As the taxonomy is now entering its twenty-second year, this review attempts to survey these investigations and appraise the findings. (Author/CP)

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.…