Officially, here (in NC), the public school has to take you, but there's no guarantee of placement no matter what you do. They could put a 15 year old in Kindergarten if they wanted to. I've never heard of it happening, but they make no promises. Other than that it's basically up to the principal, and then some will accelerate and some go strictly by age. Also in our particular district there are no gifted services other than in-class differentiation until you've been in the system for a year, no matter what kind of proof of giftedness you might have...
So... long story short, it will depend on the principal whether a transcript helps or not, and what will "pass" and what won't.
From what I've heard of the private schools around here, a handful of them are really serious about individualizing education (with a battery of placement tests in the first couple weeks of the fall semester). Others are very resistant to admitting kids who aren't a good fit for the classes already there.
I haven't done any kind of "real" transcript for anything before middle school/ high school level, just because it's so curriculum-dependent that I think it would be hard to transfer without a curriculum-specific placement test... but hopefully by Algebra it's a reasonably universal designation, and for that I'm keeping a detailed record that I could use to build a transcript if we end up needing one. I'm hoping that by the time DS might actually go to public or private school he'll have at least one AP exam behind him... but other than that I think our best bet is out-of-level standardized testing, like the Explore and in a year or two the ACT. If we did put DS in school, one of the private schools that emphasizes individualized levels and placement tests would be my preference.
