Best moment of the day: a couple of the 4th graders whose class I've been helping out in spotted me through the window at the end of the day and poked their heads in.
"You're in kindergarten? How come?"
"Well, their teacher was out sick, so they called me."
(Disgusted groan) "How come you never teach OUR CLASS?"
Aww. Give it time, kid. I'm sure your teacher's just about ready for a much needed day off.