I can see that this might have benefits for older children but if by nursery age, we mean 3 year olds, I find it hard to imagine that this is a particularly good idea. In my opinion (but obviously we all have different ones of those!), there is so little time, in the context of our children's full childhoods, for them to play and be little. Learning through play is everything at that age, following their interests and letting them explore and enjoy themselves. They'll learn proper maths and spelling all in good time and I don't see any advantage to putting them in a formal setting (with an initial test for goodness sake!) at that age. It's not a race! Maybe Kumon isn't too formal for 3 year olds so I'm v willing to be told I'm completely wrong on that