We just started our son (who's 7) out on Grade 3, their easiest level. They give assessment tests, and you can test out of things, so they'll tell you when your kid has learned 90% of the grade level and suggest you move them up. They don't have to plod through a level if it's too slow for them - just take an assessment test. If they prove they know it, without gaps, they can move up. And the next grade makes sure they keep the old knowledge up, too. If you guessed wrong your kid could move to another class very quickly, and without stress about missing important material.
