Standardized tests are devised to sort students out, comparing them on a scale from high to low, not to discover what students know. Thus, results of standardized tests are misleading in representing the achievements of educational programs and in comparing one school or school system with another. Criterion tests, however, measure directly and specifically the intentions of teaching. These tests, based on the skills which are taught and written so that students may demonstrate the extent to which they have acquired the desired learning, provide the acceptable bases for improving both schools and teaching. (JM)