Two studies involving 242 college students are described. First, a 15-item test on means was given, identifying students' misconceptions. In the experiment that followed, most students were able to acquire the appropriate schema of statistical concepts by engaging in diagnostic activities embedded in a feedback-corrective procedure. (MNS)

A model of qualities of mathematical activity was developed within a framework of learning goals. A clinical application of the model is described, in which ninth-grade students were given assignment projects. A hierarchy of effective guidance was established, permitting diagnostic evaluation and progressive development of mathematical activity.…

An experiment is described which started with exploratory interviews, evolved to design and administration of diagnostic tests, and led to the preparation and use of calculator-enriched teaching materials. (MP)

Three studies on the development of number concepts (counting, addition, subtraction, and place value) in seven- to nine-year-olds considered low attainers in mathematics were conducted. The search for a descriptive framework, the development of a diagnostic assessment instrument, and a longitudinal study are reported. (MNS)

Three teaching experiments are reported which study aspects of a diagnostic teaching methodology. An experiment in the field of directional quantities showed a positive relationship between the intensity of discussion and amount of learning; one on fractions and another on geometric reflections showed good two-month retention under the…