Jenny’s classroom is never consistent. In I Robot, You Jane, the set up of the room has the door parallel to her desk and with the computers in cubicals. Throughout season 2, her door is perpendicular with the door and the computers are on tables. It is unlikely she simply rearranged the first room because it would be to much of a hassel to rewire all the computers to fit a new plan. Plus, to set the computers up differently probably wouldn’t even work because computer rooms are designed with a plan in mind.

Also, her location seems to change as well. We know that the library is on the first floor because there is a door in the stacks. At the end of The Dark Age as Jenny walks away from Giles, she says she needs to get back to class and goes upstairs. Earlier when they kiss outside her room, you can see that the library is right outside her room because you can see the letters of the “LIBRARY” that is above the library doors reflected in the fire extinguisher. She has a room on each floor?

Also, in Some Assembly Required, as Giles approaches Jenny about a date, he holds the door for her and her classroom is on the left side of that hallway and there is no other hallway seen. In The Dark Age, they both walk down a hallway, take a left and her classroom is on the left.

Maybe she had more then one (or 3) classroom’s but this seemed interesting to note.