Find a way in

Anna thought that it was best to find a way back into the school seeing as she already missed lots of classes. Plus running to the woods would leave her completely exposed with no hiding spots the entire run. Once Anna saw the coast was clear she got out of the bush and started pacing the grounds looking for a door that didn't lead to the main entrance or to a classroom. She didn't know when the next class started so she had to hurry. After no luck with she eventually saw a vent low to the ground. Did she really want to go in another vent? Does she have any other options?