• Understanding some basics of the Theory of Games
• Highlighting elements on which the “Tragedy of the Commons” thesis is based

Duration: 1h

Gather all participants in a room. Explain to them that they got an opportunity to get some chocolate. What they will take along the game will be for themselves ; what will be left at the end will be for the group as a whole. 3 rounds will be organized. At each round, participants will got an opportunity to take some chocolate out of the bag that will circulate among them. They can take either 0, either 1, either several squares per round for themselves, knowing that :

• At the first round, when the game starts, there will be 90 squares of chocolate in total in the bag* ; one after the other, participants will take what they want from it ;
• At the end of the round, the facilitation team will count the remaining squares. For each pair, 1 new square will be added in the bag ;

Participants will not be taught how many squares of chocolate were left from the previous round nor how many there are at the beginning of the new round ;

• The process will be repeated 2 more times (including the reproduction of the chocolate at the end of the 3rd round).
• The remaining chocolate will be the common chocolate resource of the group for the next days.

At the end of the process, ask people to show the quantity of chocolate the got.

* Comment : The number of squares depends on the number of participants. For 28 participants, 90 squares is a relevant quantity. You should adapt it to your group in a way that if each person takes 1 square, the remaining squares by the end of the round will allow the resource to regenerate as it was at the beginning of the round. Example : Starting with 90 squares with a group of 28 persons, if each person takes one square, you will got : 90-28 = 62 squares. You will add 31 squares at the end of the round (because there were 31 pairs left), meaning that there are 93 squares available at the beginning of the round 2.

Ask participants to explain their strategy : Why did they act as they did ? Remind them that the game is not meant for judging each other. It aims at highlighting our behaviors and the strategies beyond them. Close the exercise with a brief explanation of your pedagogical choices, of the Theory of Games and of the limits of the so-called « Tragedy of the Commons » that the game illustrated.

• A nice quantity of chocolate (based on the maximum that you may need, i case nobody takes a chocolate all the game long)
• 1 craft paper bag