Originally Posted by aeh
Districts I've worked for or known policies for have looked for 95th %ile in receiving grade.
I think this is too stringent. Some prominent researchers on gifted education have a recommended an 85% threshold, within a different overall process:

http://www.davidsongifted.org/db/Articles_id_10248.aspx
Applying a mentor model for young mathematically talented students
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Lupkowski, A., Assouline, S. & Stanley, J.
Gifted Child Today
Prufrock Press
Vol. 13
March/April 1990

Quote
In the final step of the DT→PI mentor model, the student is given the parallel form of the achievement test as a post-test. The goal is for the student to score at least at the 85th percentile of the most rigorous norms for the test, thus indicating mastery of the material. Students who score lower than the 85th percentile require additional instruction and practice with the material. Those who score at the 85th percentile or above, but earn less than a perfect score on the test, require work on the topics they do not yet understand. When the mentor is satisfied that the student has adequately "cleaned up" his or her knowledge of the topic under study, the mentor and student re-enter the model at Step 2, using achievement tests and materials for the next level or topic. Thus, the student studies the mathematics topics in a linear fashion, demonstrating mastery before moving on.