Once, during my beginning orchestra class, a cellist forgot to bring the music. Mr. D., the orchestra director, placed a level three music book on her stand.
"Um, this is level three," she said.
"Oh, sorry," Mr. D. said, replacing it with a level two book.
"Uh...," she started to respond.
The director realized his mistake. Half-sighing, he took the book back, replaced it with a level one book and said, "Level one...We're still on level one."
I thought that was an interesting, passive-aggressive way of indicating that the class wasn't as far along as it should be.