Even if they do sell it I don't believe the people who buy it will be able to access it, unless they have modified their xbox.
When downloading DLC license are attached to the console and gamertag that originally downloaded it, so without either of those the players who try to put the DLC on their xbox won't be able to access it. If there is some way around this then I'm not familiar
You could just go and tell on them as technically what they're doing is illegal and teachers don't like illegal activity on school grounds. Haha, Good luck!
Did this solve your problem?
Sorry this didn't help.
Great! Thanks for marking this as the answer.
How satisfied are you with this reply?
Thanks for your feedback, it helps us improve the site.