The seat behind her has her backpack in the chair. The seat next to her on the other side has her coffee and headphones on it. The entire classroom fills with people. No more desks. A direct push from a seat-needing student makes her move her cup and headphones.
More people enter.
A girl the bitchy one must know sits catty-corner to her and asks about her backpack. My backpack does not go on the floor. Students entering the room start to sit on the floor. The professor, scanning for empty desks, asks backpack woman if that seat is empty, clearing referring to the one behind her, the seat her backpack must apparently have. She rips her backpack out of it, tosses it to the floor, cursing.