Agreed - Observation is the best proof. Another thing to look for is mixed age group situations where your child is on the younger side.
A playbased or non-academic style of school is often best. Not that they kids don't enjoy academic challenge so much as this age group is way too young to be asked to sit quietly while being 'taught' material far below their 'readiness-to-learn' level.
I wouldn't walk in saying 'my kid is advanced, what can you do for her' - rather I'd bring in her favorite poor to read and discuss, a copy any of her other academic worksheets if she does such things, and a few stories about what she does with her favorite friends and ask them - is this unusual for an X year old? What have you done with kids who are like this?
A good book for a parent at your stage is Deb Ruf's '5 Level's of Giftedness.' It can help you keep track of those developmental milestones and give you an idea of how 'unusal' you child actually is.
Welcome,
Grinity
