“…Keller's (1968) PSI, a mastery-oriented individualized teaching approach often used with college students, has an extraordinarily strong record of effectiveness (Kulik, Kulik, & Cohen, 1979; Kulik, Kulik, & Bangert-Drowns, 1990). Bloom's (1968) Learning-for-Mastery approach, a group-based teaching approach often used in elementary and secondary schools, also has a strong record of effectiveness (Block & Bums, 1976;Guskey & Gates, 1985; Kulik, Kulik, & Bangert-Drowns, 1990). Those studies do not focus on mastery testing, however; rather, they compare the effects of conventional teaching to effects of teaching systems that include mastery testing as one of their features.…”