Irena--I think it depends on the school/teacher/culture, etc. but I've had more success with gifted advocacy by stating "My child wants..." There seems to be far less push-back if the teacher is the type who sees the parent as hothousing. There are teachers out there who think that if a child is happy, there is no problem, but an unhappy, anxious, stressed child who doesn't want to do homework or go to school is more of a real problem to them. I wouldn't outright lie (if the child is actually happy with the curriculum), but it's the approach I'd try first, and I'd try to do it in a diplomatic fashion, not say "My child is bored, so you need to make your classes more interesting for him..."
edited to add, DS was at basically the same reading level for 3 years. In K he was at an O then the next teacher moved him down to an L, etc. If I had said "Well he's not making progress so I think we need to have an assessment" they probably would have completely blown me off (or laughed). He was above grade level, that was all that was important to them.
