The study had following objectives: 1) To develop a mastery-learning program in mathematics for standard III. (2) To study the effectiveness of program in terms of mastery learning in mathematics for standard III. (3) To improve the program for pupils having less than 50% achievement.

The hypothesis were: (1) At least 80% of students from experimental group will achieve 80% marks in posttest I and II CRT. (2) Students from experimental group will achieve competencies (judged from posttest II and I) significantly higher than the control group at 0.01 confidence level.

Sample comprised of 80 students including boys and girls in each group. All students are from middle economic strata of the society and belong to PCMC area. Incidental sampling was used. Pretest posttest control group design was used for the study. The treatment continued for 60 days. Posttests were conducted to check the retention of teaching, one month later the implementation of the mastery-learning program.

The split-half reliability of the pretest I, pretest II, posttest I and posttest II were 0.94, 0.94, 0.91 and 0.94 respectively.

Data were analyzed by using criteria based percentage and ANCOVA.

The study had following findings: (1) Mastery is attained by the students of experimental group in all three areas, viz., measurement, fraction, geometry. (2) In posttest-I only one student from control group achieved 100% marks in question number 2 and none in other questions. (3) In posttest II, none of the student from control group achieved 100% marks in question numbers 1 and 5. (4) As per the result of total score of posttest I and II, none of the students from control group achieved mastery, whereas in experimental group six students achieved good mastery in posttest I. Thirty-three students in posttest I and forty students in posttest II achieved excellently. One student in posttest I achieved complete mastery.