forgive me for disagreeing, but I would have a real problem there. While I'm in the room teaching, it's my room. I'm not a guest who is observing for a day, I'm a teacher and this is my class. If I'm being observed by my department chair, great. If another teacher wants to observe my class, he or she is free to set something up. But when my class meets, it's my class and I'm the teacher in the room. I don't want anyone else giving me or, worse, the kids I teach, the impression that I'm not capable of controlling my own class. When the bell rings, your class is over and mine begins. The room is now mine. If you put your stuff away I won't touch it. If it takes an extra minute or two on occasion, that's fine, and I expect the same courtesy. But that room is not yours. It belongs to the district and the taxpayers-- the same ones paying your salary and the salary of the person in "your" room teaching a group of kids. If security is a problem between periods, lock the door and the next teacher can open them up when she gets there.