Yeah Wreck, totally, school backpacks and chairs totally cause this problem. /Sarcasm
People in the Army carry bags on their backs which way around 2-3 stone (don't know what that is in lbs, something like 42lbs?). Instead of chairs, they sit with nothing to lean on or lay down on concrete floors/roads. Or sleep on grass, or in tents. Everyday. 24 hours a day. Yes they're trained for it, but come on.
6 hours a day at school, only physically carrying your backpack around for like a total of 1/2hrs if that...