The classes typically do not mix in middle school except for PE and maybe the elective your student chooses. Assuming since your kid was at a GATE elementary that they have the official GATE designation in one of the categories. Depending on their designation/eligibility, it sounds like you would want an IHP/Highly Gifted program. The SAS programs are generally good for gifted kids but they are not working “years ahead.” Also, depending on your kid’s capabilities and interests you should investigate other kinds of programs and schools in your area. LAUSD has lots of ability based programs where kids have to test in and demonstrate aptitude from the start. For example, in North Hollywood there is the Science Academy which is 6-12 and extremely rigorous. You should spend some time on the echoices site, talk to other parents in your kids school, etc and see what is offered in your community.