Why will my Surface 3 not charge, but has the light

In school we got Surface 3 tablets and we got chargers with them, but i can't find my wall plug in/wall port. I have the charger.So I have tried to use other wall plug in/wall port, but it won't charge with them. See the light on the charger goes off, but it says not charging. At school i borrowed my friends wall plug in/wall port and it will charge just fine, but with other ones it won't! I have no idea what to do, my teachers just keep saying borrow from friends, but I feel bad doing that. Please help! P.S I can't go into settings because my school locked us out of there.