School of Ghosts

Gary is a professor who loves his job very much. He is always prepared for the class and pays attention to every student, willing to teach them as much as possible. Also, professor Gary is a very responsible and organized person. His classroom is always clean and tide. He knows the exact place of everything and that makes him even more productive in his work. This morning, when professor Gary came at work, noticed that something is not as always. He noticed that many of the objects in the school were not in their places. He knows that no one stays at school during the night, so this event surprised him a lot. Gary decided to come to the school at night, in order to find out what is happening there. Is someone from the students coming here late at night or maybe some criminals use the school as hiding place? There is also a chance that the happenings in the school are supernatural, who knows?!Now, let's help professor Gary to find out what is happening in his school at night.