What is the highest level of classes you could take in middle school?

My sons middle school breaks the 7th grade kids in two groups for math. 3/5 of the classes are concidered accelerated. 2/5 are a "slower" pace. My son was placed in the accelerated class ( he had A's and B's last year) This year he is having a tough time in math. His confidence is down and he tells me that the teacher goes too fast. The teacher mentioned that we could swich him. I do not know what to do. in 8th grade the kids are in 3 groups. If he is placed in the lowest group now what will happen in the future. If he goes in with the low group will he be with a lot of behavior issue kids? I worry about his self esteem as well. Why would I want to switch him? He is frustrated with the pace and I find myself reteaching so that he can complete his homework. Is a lower grade in accelerated math better than a high grade in "slow" math.

I am told that:

Long term….it is unlikely a student can take Algebra in 8th grade if they are in math 2 in 7th. In that case, the student would take Algebra in high school.

Would love to hear some suggestions. Thanks