Ditto what NJMom said and I also wanted to mention that you might get a better idea of where he falls when you look at his percentiles as compared to 8th graders rather than the grade equivalents. For instance, DYS
qualifying criteria for a 3rd grader, when looking at the EXPLORE test, require scores between 14-16 on the various tests. Based upon my rough estimation of what little I know about the EXPLORE, that would mean that they are wanting a 3rd grader's achievement on an 8th grade test to fall roughly around the 55th-65th percentile as compared to 8th graders.
I would, therefore, assume that, if his percentiles on the 8th grade test he took were slightly above average, which it sounds like they easily should be, he might be a really good DYS candidate. I still think that you'd have a stronger portfolio application if the achievement test piece you were using for the application was one of the ones on their accepted list.
