The first little boy was called upon. He walked up to the front of the class, and with a piece of chalk, made a small white dot on the blackboard, then sat
back down.
Puzzled, the teacher asked him just what it was. "It's a period," said the little boy.
"Well, I can see that." she said, "but what is so exciting about a period?"
"Darned if I know," said the little boy, "but this morning my 16 year old sister was missing one, Dad had a heart attack, Mom fainted, and the man next door shot himself."