I just looked over his school work from last week. He is doing work 2-3 grade levels up in his class during reading comprehension rotations already. So I have that. I will also list his books, he recently read 1-30 Hardy Boys (since Christmas) and interview him on camera - he will LOVE IT!
Thanks for all the suggestions. They have helped me to group my thoughts about what to put together.
They said in their letter that they want to confirm they are admitting only children in the extremes of the population as to not stray from their mission and to not put pressure on children who don't fit that category. I think that is fair. I have no intention of putting DS7 into a situation he won't benefit from.