Congratulations on your son's strong scores!
First, I think the entire results have to be submitted, though I'm not entirely sure. I would send a quick e-mail to Davidson and ask if the achievement scores need to be submitted if you are relying on a portfolio.
Second, I wouldn't rely on the grade listings of workbooks as to the level of the work. If it doesn't impress you as likely 6th grade work, it probably isn't. It sounds like, as to be expected, he isn't really being challenged at school and thus not being given the opportunity to demonstrate an ability to work well above grade level. If it was me, I would spend a month after schooling, teaching him above level concepts and giving him the opportunity to demonstrate that ability. Personally, I would be inclined to delay submission of the application a month, so I could insure I had 3 or 4 items that all felt to me that they were clearly 2 or 3 years above grade level.
I'm not sure but if your son has an August birthday and is a year older than his classmates, then he may be judged on par with his age, with the expected portfolio showing being 2 to 3 years above his age, not his grade. You may wish to check this with Davidson, but I do recall that the requirements were above age level, not grade level.
I hope this helps!
