We are in the same boat. My DD8 (birthday yesterday) in grade 3 and she is doing 5th-6th grade level Math using Khan academy in school. We had to advocate for a while to make that happens. The school suggested grade skipping (she skipped once to 1st grade) but we do not want to send our DD to college too soon.
So, we made radical decision. We are moving to another district that promotes Gifted educaton. So the half of the students from the class will be pulled every morning for accelerated Math and language arts in elementary school. Middle school has regular/ accelerated and Gifted Math curriculum and the school will recommend the kid to go to High school for subject accleration if needed. And my DD will get IB diplopma or up to 2 years dual credit during High School. I will be commuting 65 miles each way but I do not have to worry about their middle and High school anymore.
If you do not have a choice, grade skipping may be the way to go. Check your middle and High school to see if they have pre-AP and AP classes and if they do, ask DD to take those instead of skipping. Your DD will take PSAT in High School and if she skipped too much, her PSAT score may be not as high as it should be and she may miss out on National Merit Scholarship, etc...
