Science class

Sixth grade science teacher, Mrs. Parks, asked her class, "Which human body part increases to 10 times its size when stimulated?"
No one answered until little Molly stood up angrily, and said, "You should
not be asking sixth graders a question like that! I'm going to tell my
parents, and they will go and tell the principal, and you'll get fired!"  She sat back down.  Mrs. Parks ignored her and asked the question again. "Which body part increases to 10 times its size when stimulated?"
Little Molly's mouth fell open, and she said to those around her, "Boy, is she gonna be in big trouble!" The teacher continued to ignore Molly and asked the class, "Anybody?".  Finally, Jimmy stood up, looked around nervously, and said, "The body part that increases to 10 times its size when stimulated is the pupil of the eye."

Mrs. Parks said, "Very good, Jimmy." Then she turned to Molly and continued, "As for you, young lady, I have three things to say:
First, you have a dirty mind.
Second, you didn't read your homework.
And third, one day you are going to be VERY, VERY disappointed!!!"