Vocational-technical students (n=92) and liberal arts students (n=156) were the subjects of a study conducted to evaluate the effectiveness of four instructional strategies intended to produce mastery. Strategies employed were: traditional instruction with no make-up exams; unlimited make-up exams with end of semester deadline; unlimited make-up exams with two-week deadline; and unlimited make-up exams with two-week deadline and with motivational help from an academic advisor. Vocational students were taught physics while liberal arts students were taught physical science. Effectiveness of each strategy was evaluated according to student achievement, further separated according to the IQ's of the students (high/low). Results of analysis indicated: (1) students with unlimited testing opportunities had better performance than those without such opportunities, in every case; (2) those with two-week deadlines performed better than those with end of semester deadlines; (3) students with advisor input generally performed better than those without advisor input; and (4) IQ was not a significant determinant of student performance. Descriptions of course content are included as are tabular and graphic data reflecting comparative student performance. A bibliography and sample course examinations are appended. (JDS)