#WeHateMath How To Start a Lecture on Probability

As my students filtered into the classroom, I was at my desk, idly shuffling a deck of playing cards. When class started, I got up and displayed the deck.

“I have here an ordinary deck of playing cards, which has not been tampered with in any way.”

I continued shuffling the deck and approached one of my students.

“Could you please examine this deck and confirm that it is indeed an ordinary deck, such as you might purchase in any store?”

She examined it, shook it, sniffed it, then handed it back. I approached another student.

“Would you please give this deck a good shuffle, just to make sure I haven’t pre-arranged the cards in any way?”

He grabbed the deck with a grin, cut it, shuffled it two or three times, then handed it back to me. I continued shuffling the deck and approached a third student.

“Please cut this deck to ensure that these cards are truly randomly organized.”

She did so and handed them back.

I held the deck over my head, pointed to a fourth student.

“Name a playing card, the first one that comes to your mind.”

“Seven of hearts”, she said.

“Seven of hearts!”, I announced to the class, “Now I want everyone to concentrate on the seven of hearts. Picture this card in as much detail as you can – color, texture, shape, until you feel you can almost touch it and keep this image in your mind.”

I held the deck in my left palm and covered the top with my right.

“While you are all concentrating on the card, I’m going to use the mental energies of the group to telekinetically move the seven of hearts up through the deck to the top. And I’m going to do this on the count of three. 1! 2! 3!”

I pulled the top card off of the deck and showed it to the class. Queen of diamonds.

“Huh. Do you have any idea how often this happens?”

I grinned.

“Tell you what. Why don’t we figure out exactly how often this happens?

Aaand we’re off to the whiteboard….

 

Teaching: one quarter preparation and three quarters live theater.

 

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