This was back in high school. Spring was approaching, I think. Our class had its own classroom where we would leave our jackets and change our shoes. One day at a normal time, when we were expecting to get in, the door was locked, but someone was inside. We knocked first, but no one answered. Through the keyhole we could see a small space in front of the blackboard but most of the room was hidden. It was empty. Later, the door was opened for us. It was the girls and our class teacher who had locked themselves in there when they arrived before us.
What do you think has happened there?