I think Catherine's close to acheiving mastery with everything covered in Key to Fractions. She getting page after page right with only the occasional mistake when she inevitably adds rather then subtracts or multiplys instead of dividing (those are the moments the cat jumps up beside her or the ittle brother decides a good mooning is just what we all need to brighten the day). That's mastery, right? When she's getting 90% of her work correct?
We still have to get through the last book (mixed numbers) but I'm confident she'll do fine. My only worry has been that she'll lose some of what she learned over our extended Christmas break but she's agreed that some daily review from Singapore Math's Intensive Practice won't be to onerous. After Christmas we'll be jumping back into the fire with Singapore again.