One of mine did it for a while, mainly because he hated maths, and once he'd been to Kumon for a while he hated it even more! It's very much repetition based which I felt he needed at the time. It was quite apparent in school there was a lot of flitting around in the subject, maybe a week doing fractions say, then on to the next thing and by the time the class had returned to fractions much had been forgotten, it was a common complaint from parents, not enough consolidation. There was a community centre near the school where Kumon classes were held, when we passed it one day, son said "some of my friends go there" and they did, but unbeknown to me, they were going to drama classes in another part of the building, although it was fair to say there were children from his school in the Kumon classes too.