Her teacher asked: "John, what are four basic elements in nature?"
John answered: " Fire, air, soil and.. and.."
"And what?" the teacher asked. "Try to remember!"
"And...And...And..."John was embarrassed.
The teacher knew that his pupil couldn't remember that the fourth element was water. Therefore, he gave a hint:" What do you clean your hands with?"
John excitedly screamed, " Soap!