Teacher knows her student cheated on his test, but how she proves it is so funny

In class one day, Ms. Thompson pulled Jimmy over to her desk after a test, and said, "Jimmy, I have a feeling that you have been cheating on your tests."

Jimmy was astounded and asked Ms. Thompson to prove it.

"Well," said Ms. Thompson, "I was looking over your test and the question was, 'Who was our first president?' and the little girl that sits next to you, Penny, wrote 'George Washington,' and so did you."

"So? Everyone knows that he was the first president."

"Now, just wait a minute," said Ms. Thompson. "The next question was, 'Who freed the slaves?' Penny put 'Abraham Lincoln' and so did you."

"Well, I read the history book last night and I remembered that," said Jimmy.

"Wait, wait," said Ms. Thompson. "The next question was, 'Who was president during the Louisiana Purchase?'

Penny wrote 'I don't know,' and you wrote, 'Me neither.'"