You might also think about the "ceiling effect." In an typical kindergarten, for example, most teachers wouldn't think of asking a child to do multiplication, and if the child doesn't initiate the activity there are "no signs" of giftedness. We saw a bit of this with DS in preschool. The class was doing letter of the day, "B is for ball" etc., and the teachers were absolutely shocked when we mentioned he could read. (They never gave him an opportunity to show them!)
Without group testing, I'm assuming any evaluation begins with teacher observation. If your child isn't the quiet, compliant, type, a teacher might, unintentionally, be combining observations of behavior with observations of intelligence.
Assuming you did some testing for CTD, you might consider sharing that testing.
