A father who is very much concerned about his son's bad grades in math decides to register him at a catholic school. After his first term there, the son brings home his report card: He's getting "A's in math. The father is, of course, pleased, but wants to know "Why are your math grades suddenly so good?" The son explains "when I walked into the classroom the first day, and I saw that guy on the wall nailed to a plus sign, I knew one thing: this place means business!"