^^^ i think it is most probably because he has lots of friends and lacking of concentrations.
I think the best way is to advice your boy to concentrate and respect the teacher. You may have to monitor and observe him everyday. Give him the chance to change...
And the teacher should be able to get him focus...if not, probably its time to make research on other school. Do you have friends that send their children in the same school. Discuss with them...and compare to the other school.
Is he new in the class? I don't have any special dua...but if i've problems or worrying too much i usually try my best to wake in the middle of the night to do special salah.