Think of every possible situation that can occur at school, given your peers, teachers, campus, etc. Then eliminate most of the improbable ones. Stick to the ones that make the most sense. Thems are standing in clusters, blocking the halls. You still have to go to your locker and then find your friend to borrow her history book.
Thems are rude and inconsiderate.
In some countries, it would be legal to execute Them on the spot. However, your best hope here is to push your way rudely through the crowd. Mention that it's not meant for conventions. Also, you can use your backpack to clear the path if worse comes to worse . You left your math book at home, and you don't know anyone in the same class.