A few days ago I subbed for a seventh grade math teacher.
There was a student teacher, so I expected the day to be pretty easy. It was still early in her semester, so she was a little green, but over all pretty good. In fact, the only real issue I had was that she never explained who I was.
Now, just to be clear, I am not trying to "steal her spotlight," nor am I looking for extra attention. With her Master Teacher gone, it was her time to shine and be a Real Teacher in the eyes of her students. I've been there. I get it. However, the concern I had was that I'd only been in the building once before, and the kids didn't know me. They kept watching me. I heard many whispers of, "who's that guy?"
A quick, "Mr. Stevenson is gone today, and this is Mr. C subbing for him, but I'll be teaching today" would have been more than enough to keep my presence from being a distraction.
The main teacher showed up during lunch. He kept saying, "I can't stay," but he was there the rest of the day. I proctored some tests for him. He didn't introduce me either. He just told the kids, "go with that guy."
Also...
7th Grade Girl: Do you like Justin Bieber?
Mr. C.: Never met him.