I substitute teach fairly regularly for one particular Algebra II teacher. He's an athletic coach, and often has "events" during the school week. It's a comfortable relationship. He gives me all of the requested dates far in advance and lets me know the lessons plans. I get to know his classes fairly well, and they rarely give me any trouble. I'm just "part of the routine".
Part of the routine is seeing the progression of kids in and out. Frequently, a new student hands me the printed office slip that spells out placement in that class, that hour. I let them know that I'm not the "real" teacher and do my best to make them feel welcome. "We're glad to have you. Where are you transferring from?"
Often it's not terribly exciting. Just changing classrooms and teachers because of a schedule conflict. Sometimes, coming from another local school. Less frequently, a move in from another city and one day last fall I met a young lady displaced to our school by Hurricane Katrina.
Today's transfer student was a bit more unusual. In a quiet, shy voice, he told me that he had come from Zambia.
Welcome. I hope you are happy here.