I just wanted to say hang in there! I agree that it is worth pushing more on the grade skip - I think everything you already did (pointing out IAS, etc) if you keep pushing on it will eventually break them down. The fact that it didn't work for another child has no statistical relevance to whether it will work for your child- point it out and turn the numbers around on them (using IAS and N.D. etc).
I know it must be so frustrating that their lack of knowledge with the earlier grade skip is now causing you issues - but keep at it.
Good luck and hang in there. I agree that you need to give them a way out. Cat
