Ditto what 'Neato said.
Though I guess my biggest wake-up-call actually came from the achievement test results (Woodcock-Johnson III for us, administered by the school to ID for GTness). That led to our getting IQ testing for him to confirm what we saw on the WJ3.
Still, knowing that his ability and potential were well beyond what material we had been giving him made a big difference in how DH and I have approached his education, and it's been for the best. He's much happier now that he's actually being challenged.
