Skit: Knights and Knaves Logic Puzzles

photo by puuikibeach via flickr

Our homeschool co-op held an end-of-semester assembly. Each class was supposed to demonstrate something they had learned. I planned to set up a static display showing some of our projects, like the fractal pop-up card and the game of Nim, but the students voted to do a skit based on the logic puzzles of Raymond Smullyan.

We had a small class (only four students), but you can easily divide up the lines make room for more players. We created signs from half-sheets of poster board with each native’s line on front and whether she was a knight or knave on the flip side. In the course of a skit, there isn’t enough time to really think through the puzzles, so the audience had to vote based on first impressions — which gave us a fair showing of all opinions on each puzzle.

Knights and Knaves Skit

Setting

EXT.: THE BEACH OF A TROPICAL ISLAND – DAY.

Players

NARRATOR 1, NARRATOR 2: Our “tour guides” to the Island of Knights and Knaves.

NATIVE 1, NATIVE 2: Islanders who talk in cryptic sentences.

PROP MASTER: Makes sure Natives have the correct signs to hold up for each puzzle.

Action 

NARRATOR 1
A terrible thing has happened! You were enjoying your Pacific Ocean cruise when suddenly, a horrible storm came up. Huge waves crashed over the deck, and you were swept overboard.

NARRATOR 2
In the morning, you find yourself alone, cast ashore on an island beach. You struggle to your feet and see a large rock with words carved into it: “Welcome to the Island of Knights and Knaves.”

NARRATOR 1
You have heard stories about this island, but you thought it was a myth. You know there are two types of natives here: Knights, who always tell the truth and never lie; and Knaves, who always lie and never, ever tell the truth.

NARRATOR 2
Logic means learning to discern, to tell the difference, between what is true and what is false. So think carefully. Can you tell who is lying and who is telling the truth?

[While Narrators are speaking, Natives pick up their signs for Puzzle #1. Remember to keep the answers hidden!]

First Puzzle

NARRATOR 1
As you walk down the beach, you meet two islanders fishing in the lagoon. They say to you:

NATIVE 1
[hold up sign] One of us is a Knave.

NATIVE 2
[hold up sign] We are both Knaves.

NARRATOR 2
What do you think? Is either of them telling the truth? raise your hands to vote. [point to Native 1] How many people think this one is a Knight? [pause] How many think Knave?

NARRATOR 1
[point to Native 2] Is this one a Knight? [pause] A Knave?

[After audience has time to vote, Natives turn their signs to reveal the answers. Then Natives step back to get their signs for Puzzle #2.]

Second Puzzle

NARRATOR 2
You are getting hot, so you walk over to some palm trees. You see two islanders sitting in the shade. They say to you:

NATIVE 1
[hold up sign] We are both Knights.

NATIVE 2
[hold up sign] She is a Knave.

NARRATOR 1
What do you think? Raise your hands to vote. [point to Native 1] Is this one a Knight? [pause] A Knave?

NARRATOR 2
[point to Native 2] Is this one a Knight? [pause] A Knave?

[After audience has time to vote, Natives turn their signs to reveal the answers. Then Natives step back to get their signs for Puzzle #3.]

Third Puzzle

NARRATOR 1
You see a path into the woods. You follow it to the village, where there’s a fiesta going on — an island party with plenty of great food. At the fiesta, you meet two more natives. They say to you:

NATIVE 1
[hold up sign] At least one of us is a Knight.

NATIVE 2
[hold up sign] Exactly one of us is a Knight.

NARRATOR 2
What do you think? Raise your hands to vote. [point to Native 1] Is this one a Knight? [pause] A Knave?

NARRATOR 1
[point to Native 2] Is this one a Knight? [pause] A Knave?

[After audience has time to vote, Natives turn their signs to reveal the answers. Then Natives and Narrator 1 step back.]

NARRATOR 2
That’s all for our visit to the Island of Knights and Knaves. We hope you have enjoyed this adventure in logical thinking.

EXUENT.


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