"Turn this mouse into a snuff box," instructed Professor McGonagall when it was time for the practical portion of transfiguration.
Harry knew he had done poorly on the theory side of the subject, since he only really wanted to understand the use of the magic and not the metaphysical stuff behind it. He wasn't too worried about failing the practical, but it went against his nature to just do what he was asked without some attempt at avoidance.
"That's a bit cruel, isn't it?" he asked.
"I assure you that I will be able to reverse anything you do," she answered.
"Are you going to wipe the mouse's memory?" he persisted. "I mean it's all well and good that you'll make sure it's going to be a mouse again, but what if it's traumatised and gets sudden urges to snort tobacco or run up somebody's nose or something? I don't think I'd like to have that on my conscious, Professor."
"Mr Potter, I am well aware that you are perfectly capable of performing this spell," said McGonagall "So what is-"
"Oh, well I guess we are done then," interrupted Harry, turning and leaving the classroom, a huge smile on his face. "Thank you."
He actually made it two steps out of the door before his teacher found her voice and called him back.