The WJ III and the WIAT actually do have questions from various grade levels, so their scores mean that the child answered questions at that level. The caveat with those scores is that the number of questions asked at each grade level is extremely small and from about middle school and up they have extremely low expectations of what grade level means. I think I read that 12th grade level math on the WJ is algebra. But for most of the achievement tests given in the classroom, their grade equivalents aren't really equivalent.
