Hmmm.
I'd probably attempt to make suggestions to the teacher which allow her to maintain her regular classroom routines as much as possible WHILE giving your child the opportunity to do work which
is meaningful.
I would politely express surprise at the teacher's suggestion of attentional issues, and explain that you simply don't see this behavior anywhere else, not even in fairly structured situations. THEN suggest that perhaps your child has "extra time" that he's using to tune out... diplomatic, but firm.
On that segue, you could offer to send in books that your child enjoys. That way, you and the teacher can make a deal with your DS that anytime he is "finished" with the work that the teacher wants the class to be doing (yes, including the 'preschool' worksheets, if that's her thing)... he can quietly begin reading silently.
What he CAN'T do is interrupt and prevent his classmates from learning.
That way the teacher feels that she's getting something in the way of better behavior from him, and HE will be gaining an opportunity to do something meaningful with his school day and to demonstrate to the teacher what the REAL problem is here.
At that point, you could suggest that he's perhaps in need of something for math, too.
