First time post here...
I have a just-turned-11-year-old 6th grader, who had been accelerated 1 year in a full-time elementary gifted program and is now excelling in middle school honors (e.g. 7th grade math, 12.9 reading level). So far her only formal assessment was with the Woodcock Johnson test when she was 4 years old, and she'd scored the highest classification (Very Superior).
From what I've read, at this grade level the most appropriate test for re-assessment is the ACT. I want to get an accurate representation of where she's at now, and resist the urge to over-prep or over-coach.
So how much prep is appropriate? I.e. where's the line between making sure she's prepared enough for the test to let her true abilities shine through, without having her "prep" so much that it skews her results?
The CTY site site for talent sarch participants
http://cty.jhu.edu/talent/testing/about/act.html has a "Preparing for the ACT" booklet with sample questions. Before my 4th grader took the SAT I had him work through the book "Math Study Guide for the SAT, ACT and SAT Subject Tests" by Richard Corn. In general, I would try to expose my child to all the math concepts covered on the test and would not worry about this biasing the result. For most 11-year olds, SAT/ACT test prep would raise their scores very little, because the concepts would be over their heads. The ability of test prep to raise the ACT score of an 11yo is related to giftedness IMO.