Good luck with the principal. Our principal was very helpful. Our school has no GT programming until 3rd grade, and we're in a K-2 center, so nothing at all. That said, since we told them about our DS's IQ scores, and they tested him on their own achievement test as well, they were willing to try to differentiate for him. The principal has the power - maybe even the power to switch you to a more open-minded teacher (if there's room in other classes). Or to have your DS move to a higher grade class for some subjects. I highly recommend getting the principal on your side. Good luck!
