A teacher was leaving the staff room when she found the Principal standing in front of the paper shredder with a piece of paper in his hand. “Listen,” said the Principal, “this is important, and the secretary has left for the day. Can you make this thing work?”

“Certainly,” said the teacher. She turned the machine on, inserted the paper, and pressed the start button.

“Excellent, excellent!” said the Principal as his paper disappeared inside the machine. “I just need one copy.”