Tragedy of the Commons: Lesson Six of the Climate Change Curriculum


Tragedy of the Commons” is a key work in the discussion of the morality associated with the exploitation of resources and the human causes of climate change. The concept is that a group of people sharing a resource that no one owns, such as air, will exploit it to the maximum possible capacity without taking into account the needs of others or the sustainability of its use. For example, when a group of cattle herders have free access to a field, each one will continue to increase the size of the herd because they have no incentive to stop. However, the field will soon be overgrazed and no one will be able to use it. This can be prevented by regulations and agreements between people using resources such as water, fisheries, forests, etc.

A more age-appropriate summary can help leaders with explaining the concept to participants.

Learning Objectives

  • Understand the concept of overexploiting resources
  • Come up with solutions for the Tragedy of the Commons
  • Debrief the climate change topic and actions to be taken

Chalice Lighting

(5 minutes)

Use the words below or one you find yourself.

We light this Unitarian Universalist chalice
with open minds, helping hands, and loving hearts.


(5-10 minutes)

Go around in a circle or have participants randomly share how their week has been. Remind them to be respectful of whatever each person has to share and to keep their thoughts brief. It is important to make a space where everyone feels safe and comfortable and to respect where each person is coming from that day. If time allows, go around twice; once for news and once for joys and sorrows. It is important that the leaders participate in the check-in to build a relationship with the participants.


Read the story from NOVA about resource competition and depletion. You can have participants briefly discuss how the Easter Island could be an example of what could happen to the earth. Before reading, have your students find Easter Island on a map or globe.


M&M Fishery

(20-30 minutes)


This activity simulates the Tragedy of the Commons to help participants understand what happens when resources are overexploited without regulation.


  • Large bag of M&Ms, Skittles, or similar candy
  • Straws (1 for each student)
  • Paper or plastic plates (1 for every 4 participants)
  • Small dishes or plates (1 for each student)
  • Paper (1 sheet for each group)
  • Markers (1 for each group)


Tables to fit four participants each.


NOTE: Check for allergies and don't get candy with nuts.

  1. Explain to participants that they are going to do an activity about resource exploitation. Break them up into groups of four and group them around the tables. Give each a plate with two candies per person in the group. Provide each person with a straw and small dish.
  2. Explain that each group is a fishing village, and each person is the head of his or her family. To provide for them for a year they must collect two fish, or candies. However, they can collect as many as they want during the time allotted. To collect fish they must use the straws to suck the candy up (emphasize that it is not sucked into the straw, but held by suction at the end) and move it into the dish. Allow the participants 45 seconds to 1 minute for each season, and remind the participants that they cannot talk during the fishing season.
  3. After you have called the time on a season walk around and put one candy on every plate for every candy left. Take the straws from anyone who did not collect at least two candies. Then have the participants fish for another “season.” Repeat this two or three more times. Ideally, groups will begin to run out of candies because they “overfished.”
  4. Once the final season is over, gather for a discussion. Feel free to pass out extra candies to the participants. Ask the participants what they thought of the activity. Were they able to feed their families for all of the rounds? How many fish did they have left at the end compared to the beginning? For the people who had to stop because they didn’t have enough fish, was it fair? Why could they not get enough? Students do not need to share if they don’t feel comfortable.
  5. Explain the concept of the tragedy of the commons. Ask the participants to draw connections between the activity and the larger concept. Can they think of any other situations this idea could apply to? What could be done to prevent over exploitation?
  6. Have the participants re-form their groups and hand out paper and markers. Ask them to come up with a set of rules that would prevent overfishing of the M&Ms.
  7. Come back into the large group once more to share the rules each group came up with. Who would create rules like this in a real fishery situation?

Presenting the DOT Projects

(30-40 minutes)


  • Blank printer paper
  • Markers
  • Tape, stapler, etc.


Tables or floor and a large blank wall.


  1. Explain to the participants that, now that they have completed their Do One Thing projects, they will share their experiences with each other and the community.
  2. Give each student a piece of paper and put the markers in an accessible place. Ask them to make a little poster explaining what they did for their project. They should include their name, what they did, and what they will do in the future to continue to work against climate change. They can illustrate it however they would like.
  3. When they are finished with their posters, invite each student to share briefly what they learned by doing their DOT project and what they will do in the future. Once everyone has shared, put the posters up on the wall with a brief explanation of the DOT assignment. Alert parents and guardians to where they are.
  4. You can encourage participants to enter their DOTs.
    NOTE: If possible, invite parents and guardians to be present when the participants present their projects.


Have one student extinguish the chalice while everyone reads the closing words.

We extinguish this flame but not the light of truth,
the warmth of community,
or the fire of commitment.
These we carry in our hearts until we are together again.