What is the school's explanation for his behavioral problems?
Have they even attempted to evaluate what might be at the bottom of it? You state underachievement-- so shouldn't the school be interested in this, too??
Sheesh-- what if it
were a communication/interpersonal disability or a mental health issue?? Wouldn't they have an obligation to exercise child-find procedures?
I'd ask what they feel will benefit your CHILD in their recommended "placement change" at this time.
If there isn't anything, challenge them to provide evidence that his conduct is having a negative impact on other students, firstly, and secondly, that there is "nothing" more that they can do about this.
OF COURSE go in with documents in hand-- because that may open the door to accessing higher level material.
Have you considered a grade skip directly into high school?
