That is really good Jase.....besides working out, what else did you do? My son is wanting to beef up and although he is working out a lot, he can't seem to put on pounds. He is only 16 and I refuse to let him have supplements.
don't let him if he's obviously still growing.
if he's as tall as he's going to get, there's really not much you can do. He has to fill out naturally. Most people don't hit their physical stride until their mid twenties, it's just that they've become completely sedentary by then and it doesn't matter.
there's really not much harm in protein shakes, but at his age there isn't much point either. just make sure (and this is if he's still growing. if he's 5'2 with size 13 feet he's not done) he eats a healthy diet, high protein, lots of good calories.
but honestly being a full time student + homework really doesn't lend itself to serious working out. the time commitment as well as diet dedication is really hard to do, especially when you've been at class all day and OH MY GOD A BAG OF OREOS