Ds uses a trolley to carry his books around school. For the last 2 days he's been without it (one swing up the steps too many and it's now kaput) and he's had to revert to a back pack whilst I've looked for a new one. His bag contains a pencil case, a laptop, a charger, text books and exercise books, the usual stuff, but it's so heavy he can hardly carry it and looks a little hunched over. He does have access to a locker at school but he has to carry all of this too school and from school, and he doesn't always have chance to get to where it is in between lessons. Prior to me buying the trolley for him he was missing a lot of school due to back pain and exhaustion. After he began using the trolley his attendance shot up.
I had a look online and there's loads of health problems associated with this so I thought I'd mention it. If your child's exhausted all the time and suffers from a sore back, then it's worth considering.
I'm not plugging anything, honest.