I've just had my son's end of term report and the same thing crops up. He is academically bright but is far too chatty and doesn't concentrate in lessons. It is holding him back as he could do even better.
I've just googled some advice and he does get plenty of exercise (he does sport every day at school and mostly afterwards); has plenty of sleep; eats well and doesn't spend that much time in front of the TV or ipad.
He is a July baby and just quite immature. I've told him that he needs to concentrate and not chat so much and he says that he tries but can't seem to last the whole lesson particularly if people are discussing things he finds interesting. I appreciate that it's annoying for the teacher and distracting for the other boys which I have pointed out as well.
I don't know what else to do to help!