We are in the same situation with our children, who are in similar grades. Also a public school, does not allow grade level acceleration, subject differentiation, or mandatory GT programming. We have met with the administrators many times over the years to no avail. We have come to the conclusion that that the principal does not want to take on any additional work to accommodate students' unique learning unless absolutely necessary such as SPED.
Therefore, we have decided that school will just give our children some socialization skills, group work involvement, field trips, and comply with state testing assessments. The real learning happens at home after school. However, we felt our kids were in school too long and it wasn't right that they would come home and do more schooling, and have less unstructured free time. So we brought up the idea of partial home schooling and traditional schooling, and it seems to be favorable with the administrators. It doesn't involve any more work for them, as we will just pull our kids out of school at lunch break. It is the best of both worlds. We plan on doing the early pull out three times a week and two times a week they stay in school the whole time. Our state actually does not have a mandate on partial homeschooling so it is important to have the principal be on board with this plan.
Sunnyday, since you mentioned you help out in the classroom a lot, you could try partial homeschooling in the morning and have them join in the afternoon or vice versa like us. Even try it just two times per week or whatever accommodates your schedule. It is kinda like the old saying "if you want to have something done right, you need to do it yourself." You can't depend on the public school to teach your kids to the level you think they deserve and provide them with individual attention. It is just not feasible for the school to attend to every single child's differing learning needs and abilities.
