I think the additional documentation would be specific to your DS's situation. If you apply and they ask for additional documentation, you can always call them and ask what type of additional documentation is best. For us, the initial referral was to the portfolio portion of their website, which now reads:
A portfolio with three original pieces of the applicant�s work that demonstrate his/her advanced precocity. In order for the Applications Review Committee to best assess the applicant�s abilities, please submit work that showcases your child�s academic areas of strength. The Committee prefers to see independent work that is 2 to 3 grade levels above age peers and work completed without the assistance of teachers or parents. Some of the most informative samples have included intellectual activities the applicant has completed just for fun, such as math �doodles�, creative writing, or autonomous projects. DVD/videotape recordings demonstrating your child�s academic abilities may also be included. Please briefly describe each item, including the applicant�s age and grade level at the time of completion, as well as the circumstances of the work (i.e. if it was completed independently, as part of a school project, how many times the work was revised, etc.), so the Review Committee is able to view it in the context in which it was completed.
This language has changed since we submitted our additional materials this past July. This is actually easier for me to understand. The old language referred to a theory of learning - can't remember what it was called (maybe Bloomberg? Taxonomy?). The gist of it was to show the ability to synthesize, analyze and create new ideas based on knowledge rather than demonstrate rote knowledge. Something like that.
Good luck!
