So sorry to hear that things are going so poorly. If you dig around here you will see that...
1) Kids who are learning nothing in school at age 5ish may,depending one their personality, be miserable and be poorly behaved.
2) Giftedness isn't a one size fits all propositiion....but it is a one size fits most sort of thing. Consider the shape of the bell curve's Right hand tail...most kids at the cut off and fewer and fewer at higher and higher levels of unusualness. Some very unusually hightly kids have wonderfully advanced emotional maturity so they can deal with a poor fit situation but others are average 5 year olds. Look for the phrase LOG or Levels of giftedness. BTW it is perfectly possible for a parent to be a high LOG of giftedness and feel themselves to be stupid. The more one knows the more one may be aware of their human limitations.
3) Some kids are gifted 'and.' This maybe a learning disability or AS or ADHD or OverExcitabilities or slow prossessing speed or low working memory. This can cause the child to be ill at ease or exhausted or difficult for a teacher to appreciate.

You may have had an IQ test to qualify for this school. If the test was given by an educational psychologist call this person right away and get some insight.
Call the teacher and set up a meeting ASAP. This doesn't work for everyone but some people would consider a visit to the principle and cry about how sad it made you to see how unhappy your child was and how your efforts didn't correct the situation. Schools seen to 'speak' social and emotional needs.

It is a long shot.

I would strongly urge you to visit some other schools and observe a variety of classrooms. You may find,for example, that it would take placement in 2nd or 3rd grade for your child to be learning even 20% new material. Most gifted people have very little idea what is normal developmental levels for small children because adults tend to collect friends and family from people who are generally of a similar IQ level...at least moresore than a classroom.

Please let us know how things go.
Grinity


Coaching available, at SchoolSuccessSolutions.com