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1.5: Demonstrations for Chapter 1

Difficulty Level: At Grade Created by: CK-12

The Seven-of-Diamonds Game

This is the easiest of the observation and hypothesis games. To play the game, the teacher must select and instruct an assistant to play the role of “psychic.” The teacher draws the seven-of-diamonds set up on the board as shown below.

To begin the game, the “psychic” is sent out of the room. While the psychic is out of the room, the students select one of the cards and inform the teacher which card. Then the psychic is called back into the room and the teacher points to one of the cards and asks the psychic, “Is this the card?” The psychic responds either “yes” or “no” and the process continues until the teacher points to the correct card and the psychic correctly identifies the card as the one the students had selected. The students are to observe the game and after each trial run, make hypotheesis about how the trick is being done. They can do this as individuals or in groups. the game can be played over and over until at least one student or group figures out how the trick is being done. When a student or group thinks they know the trick, they can go out of the room with the psychic and then play the role of the psychic when they return. If they can correctly identify the selected card, they win the game. The game can continue until more students figure it out or the winners can explain the trick to those who didn't figure it out.


The layout of the cards on the board and the spots on the seven-of-diamonds exactly correspond. The psychic will not know the correct card until the teacher points to the seven-of-diamonds and asks, “Is this the card?” When the teacher points to the seven-of-diamonds, he/she points to the spot on the card that corresponds to the card selected. In the picture above, the teacher is pointing to the spot on the seven-of-diamonds that corresponds to the position of the “6” in the layout. Therefore, the six-of-diamonds is the selected card for this trial. The psychic continues to say “no” until the teacher points to the six-of-diamonds and then says “yes.” You should note, it is not possible to have the psychic identify the correct card on the first try unless the selected card is the seven-of-diamonds. If the seven is the selected card, the teacher can point to the seven first and point to the center position. The psychic must be alert to get this one. The teacher can vary the sequence of asking so that sometimes, the selected card is pointed to on the second try or the fourth try, and so forth.

“This” or “That” Psychic Game

This is the most difficult of these observation/hypothesis games for the students to figure out. The teacher draws 3 columns of 3 squares each on the board as shown at right. Once again, the teacher needs an assistant to act as psychic. Secretly, the teacher and the “psychic” conspire and assign the two outside columns to be called “this” columns and the middle column to be called a “that” column.

As usual, the psychic leaves the room and the students select one of the squares to be “psychically” identified. The psychic is called back into the room and the teacher proceeds to point at various squares and ask the psychic, “Is it this one?”, or “Is it that one?” The code known only to the teacher and the psychic is that if the teacher uses the correct name of the column when inquiring about a square, the psychic answers “no.” If the teacher uses the incorrect name of the column when inquiring, the psychic replies “yes.”

One of the things that make this game so difficult is that the teacher can ask about the correct square on the first try. On the very first trial, the teacher can point to a square in the middle column (the “that” column) and ask, “Is it this one?” and the psychic replies “yes.”

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