The 8th grade science teacher, Mrs. Parks, asked her class, "Which human body part increases to ten times its size when stimulated?"

No one answered until little Mary stood up angrily and said, "You should not be asking eighth-graders a question like that! I'm going to tell my parents, and they will go and tell the principal, who will then fire you!" With a sneer on her face, she then sat back down.

Mrs. Parks ignored her and asked the question again: "Which body part increases to 10 times its size when stimulated?" Little Mary's mouth fell open. She said to those around her, "Boy, is she going to get in big trouble!"

The teacher continued to ignore her and asked the class, "Anybody?"

Finally, Billy stood up, looked around nervously, and replied, "The body part that increases 10 times its size when stimulated is the pupil of the eye."

"Very good, Billy," said Mrs. Parks.

Then, turning to Mary, she said: "As for you, young lady, I have three things to say. One, you have a dirty mind. Two, you didn't read your homework. And three, one day you are going to be very, very disappointed."