The thing is, in order to score 98th+ percentile on achievement tests, you have to be taught above grade-level.
*Very* quick reply here as I'm in a hurry, but fwiw, I think this must depend on the test. This is just a very quick example for you, but both my EG ds and my MG (if that) dd have been through the same language arts/etc curricula for the past few years. My MG actually is more "successful" at the curricula - she's a talented writer and grammar/etc all come very naturally too her with little effort. She's the kid who after-schools herself in LA activities. DS, otoh, is a total math/science nerd. Yet ds consistently scores up above 98th percentile on LA (reading, verbal, grammar etc) achievement tests that their school uses (nationally normed tests), and dd scores consistently lower. Both of their scores make sense if you look at it relative to their ability scores.
polarbear
