The experimental study was designed to determine the effectiveness of Kumon method in comparison with traditional lecture method in the teaching of Mathematics to grade-6. The objective of the study was to determine the effectiveness of Kumon method for academic achievement of children in Mathematics. All students of grade-6 of Fazaia Inter colleges of Rawalpindi and Islamabad was the population.Cluster sampling technique randomly was used. One of the three Fazaia colleges (Grade-6) was selected randomly. All grade-6 students of theselected cluster formed the sample of the study. Data was collected and analyzed by applying t-test and recommendations were given on the basis of findings of the study. This study shows that Kumon method is more effective for teaching mathematics to Grade 6 students in comparison with traditional lecture method and equally helpful in teaching mathematics effectively to boys and girls.