BTW, I second the "may not be ready" thing.
Just because they know the concept doesn't mean they're ripe for memorization. At 6, my DS had totally mastered the concept, but CLEARLY wasn't ready to memorize. Nothing stuck, and he wasn't at all interested.
So we shifted gears and did geometry for a while, since that was perfect for his visual style, hunger for concepts, and lack of interest in computation. It was completely out of the normal math path, but it worked for him. Now, a year later, he's much more interested in computation and is gradually learning his facts. (He still hates flash cards--visual kids don't usually have any great love for those...)
That's the main reason I resist "drill and kill" for my 7yo. If he were 9 and still hadn't learned them, I'd be pushing a lot harder. As it is, I think making it appealing so that I can keep throwing it at him regularly seems to be a better approach. Not that I think life has to be a party, but that he's doing it early, so there's no need to make him miserable along the way, you know? You catch more flies with honey and all that...
