A woman teacher asked a zoo keeper during a zoo visit with her 4th grade class, "What is the difference between the North American porcupine and the African porcupine ?"

"The principal difference between them Miss," the attendant replied, "is that the North American species has a longer prick."

The teacher fled in distress and anger to the Administration Building where the Chief Curator attempted to mollify her.

"I apologize for my staff Miss." he said. "It was an unfortunate choice of terms. What the keeper should have told your children is that the North American porcupine has a longer quill."

"Their pricks are exactly the same size."