Originally Posted by Val
What they mean is this:

Say your nine-year-old takes an achievement test and the results for, umm, math computation are the 99th percentile, with a grade equivalent of 12.9. laugh

This means that an average graduating high school senior taking the same test would be expected to get the result your child got.

It does NOT mean, as the OP suggested, that you should ship your nine-year-old off to college. shocked He might cry. Mine would. frown

If at age 9 my son scores as well as the average MIT freshman on the SAT I and the SAT II subject tests, then I will have him use MIT Open Courseware and other resources to study what those students are studying, at least if my son wants to do so.

I think grade equivalents are more meaningful and useful than Z-scores. If the 9yo scores better than the average 6th grader, maybe he should be studying 7th grade math. If all you know is that he scores 2 standard deviations above other 9-year-olds, what does that say about what he should study?

"To see what is in front of one's nose needs a constant struggle." - George Orwell