This question really depends on the camp location & type of camping. For example, if your son is going pull up camping, then a regular duffle bag would suffice. However, If there is any kind of length from travel vehicle to the campsite (Hiking with equipment, etc.) then a backpack with support straps around the waist and chest would be preferable. It's important to pack enough equipment so that he has everything he needs. However, this does not mean to overpack him or to buy every neat little gadget that is in the camping section at your local sporting goods store. The barebone essentials is a means to transport equipment (dufflebag or backpack), enough weather apropriate clothes for the weekend + 1 outfit, additional socks (at least 4 pair), boots, a flashlight with spare batteries, a tent with a ground tarp and a rain tarp, sleeping bag that is weather appropriate*, a sleeping pad is helpful, apropriate amount of food if not included, mess kit (usually 2 bowls, a plate, a cup all together) eating utensils, a small rain poncho, A sweatshirt for night time, genral hygene maintenance**, water bottle. There are some other things that are needed but may be provided by the supervising adults. These things include first aid kit, matches, fire starters, cooking utensils as well as a stove and fuel, dishsoap, means for water purification, and a few other misc. items. Remember, espicially when your son first starts camping, he won't remember to pack everything, and if amazingly enough he does..............he won't be able to find it when he needs it. maybe he'll just forget he packed it. What i'm saying is, remember the important stuff, and let him get by. He will either improvise or won't need it as bad as he thought. Lastly, I'm sure he's not going out alone. People who go camping together generally have more supplies then they need, so everyone helps each other out.
* Sleeping bags are temperature rated. Some go as low -15F degrees. Generally, the $40 bargain coleman bags from walmart, etc. are rated for 35F degrees and are supposed to be used spring, summer, and fall.
** As far as camping hygene goes, unscented soaps are best. Scented soaps attract animals to your site and they may tear up your site. Also, odds are you son won't be the most hygene conscious person while he is out in the woods. It's just a fact that most kids are not, espicially during there first trip. He will be fine. Pack it for him, but it will most likely return unused.
I hope this helped. Good luck. I'm sure he will have a blast.