Most kids that age haven't cured cancer or written a novel yet, no matter how GT they are. No worries there.
I'll give you my standard recommendations: think about what she's doing in those times when you find yourself raising an eyebrow and thinking, "Wow. That's not normal, right?" If you can, get some video of her in these times, preferably attaching whatever she was working on at the time (math sheet, writing, science questions, imaginative play, building project, etc.). This gives them a LOT of information about your child's abilities. I really think that if you see an HG+ child in action, you know it.
Also, whatever you send, I recommend that you keep in mind that it needs to show not only that your child is GT or MG, but that she is HG+. They're not looking for MG. You'd like to show that she's working at least 3 grades above level, I think.
Best wishes!
