My guess is if the school is overseeing it, you don't need to worry too much about tracking his progress--they will make sure he's on target to meet the needs of the class. I would ask him which class he wants to be in next year and whether he wants to dedicate time over the summer to it. I personally don't think it's worth pushing him ahead if he doesn't want to do the work--too many risks of blow back with this age.