I agree with lucounu, I wouldn't worry about the small drop in scores - could be any # of reasons. If there's a drop in percentile, it's most likely not from your dd "flattening out" but rather due to beginning reading skills happening across a spectrum in a wide variety of skills - that's what I've always understood the "3rd grade flattening out" statement to mean - children who start reading early aren't necessarily going to be the children at the top of the reading pack in 3rd grade because not all children start reading early (not even all gifted children). There are also probably a number of children who's reading scores are depressed in early elementary due to vision or other challenges who "catch up" to where they would have been without the issue once their challenges were recognized in school and corrected or accommodated. I've got two of those kiddos - one with visual challenges, one with a memory challenge. They both made huge leaps and bounds in reading skills, speed and comprehension between 2nd and 3rd grade.
polarbear