In Japan, teachers don't have classrooms. The kids keep the classrooms and the teachers share a group office even worse that cubicle farm. When the kids want someone, they come to the door of the office and yell "Sensei!" which is completely ignored by the 50 people in the room who are all "Sensei."
I remember that from when I taught in Japan. It also took a bit of getting used to when I would go to a shop and the shopkeeper would call me sensei. (It was a small town and I taught the children or grandchildren of just about everyone in the area, so they all knew who I was.)
Actually come to think about it, there were some situations when I had some of my school students in the aikido class with me, and my sensei would call me sensei. That was weird.