Teachers, who are adept in the subject, rack their brains and generate new worksheets with a support answer key to guide the instructor. There is no limit to the number of worksheets you generate for the class or tutorials and they can be used for distribution purposes.
For seven years I've watched my beautiful son hunched over Kumon math worksheets. He finds little enjoyment from them and I'd rather see him chasing butterflies. They've certainly helped his Math performance at school __ he's top of his class, but I wonder if the effort has been worth it in the big scheme of things. He's currently solving about 100 polynomials per day. Man, he can really solve polynomials, and fast. But for what?