TRAGEDY OF THE COMMONS (1 HOUR)
In this activity students will play a simple game designed to simulate
the situation known as “the tragedy of the commons.” Students will
later work together in groups to craft rules for sharing resources so
that those resources are not overused.
Overview
Topic: Tragedy of the Commons
Real World Science Topics:
•
An exploration of the relationship between people and their environment.
•
An exploration of the how people regulate their use of resources.
Objective
Students will gain an understanding of how and why people have to work together in order to
prevent overuse or destruction of natural resources.
Materials Needed for Each Team of 2-4 students:
several hundred beads or other small objects (at least 200 for each group)
plate
20-30 rewards, such as stickers, or small toys
Standards Met
National Science Standards Addressed
Content Standard A: Science as Inquiry
Students:
•
Think critically and logically to make the relationships between evidence and explanations.
Content Standard C: Life Science
•
Will understand that humans depend on their natural and constructed environments.
Humans change environments in ways that can be either beneficial or detrimental for
themselves and other organisms.
National Math Standards Addressed
Problem Solving: Apply and adapt a variety of appropriate strategies to solve problems.
National Technology Standards Addressed
Use models and simulations to explore complex systems and issues
Sources:
National Science Teachers Association
http://books.nap.edu/html/nses/overview.html#content
National Council of Teachers of Mathematics
http://standards.nctm.org/document
National Educational Technology Standards
http://cnets.iste.org/currstands/cstands-netss.html
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STEPS FOR
TRAGEDY OF THE COMMONS
1. Warm-Up Activity:
Ask students to think of resources in the classroom that are available for anyone to use.
These may be things such as books, a computer, or school supplies. Ask the students what
prevents one student from using each resource all of the time or using it until it runs out.
They should answer that there are rules that limit how much each student can use each
resource. Explain that people use natural resources, such as plants, animals, air, and water,
every day. Explain that, like classroom resources, natural resources can also be overused if
there are no rules guiding how people use them. These resources can disappear or become
useless if too many people use them too quickly. Tell students that in this activity they will
perform a simulation of a situation of a common problem called the Tragedy of the
Commons.
2. Divide the students up into groups of four. One student in each group, the recorder, will
keep time, distribute and count the beads, and record the results. (If you wish, you may
divide the recorder duties among the students, or rotate the duties between students.)
3. Provide students with the Tragedy of the Commons handout, which provides the rules
of the game, as well as a place to record the results of each game. The rules are also listed
below if you would like to write them on the board so students may reference them
quickly.
•
Each group starts with 100 beads on its plate.
•
You get one reward for every 10 beads you pick up.
•
To continue to the next round, you have to collect at least one reward
in each round.
•
Each round will last 15 seconds.
•
At the end of a round, the recorder will count the number of beads each
student has picked up, and hand out rewards.
•
The recorder will double the number of beads remaining on the plate
after each round.
•
The person with the most rewards after five rounds wins.
4. The beads could actually be any small object that would be relatively easy to pick up.
This could include buttons, paper clips, or candy. To save time, before class, count out 100
beads or other items for each group and place them in a plastic bag or other container.
Place the remaining beads in a larger container. The recorder for each group should take
beads from this container to replenish the supply on the group’s plate after each round.
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STEPS FOR
TRAGEDY OF THE COMMONS
(CONT)
5. Play five rounds of the game. After students have played one game, discuss the results
with the students. Ask students to record their strategy, if they had one, on the handout.
There is a good chance that most or all of the groups will have run out of beads before the
game is over. Explain to students that this is actually the point of the game. The technical
details of the tragedy of the commons will be beyond most students, but explain to them
that when people have a good reason to use a resource, they will often use it until it is
gone, unless there are rules that stop them. Explain that, in this scenario, the beads could
represent fish in the ocean. Ask them to think of ways that the beads are like fish. Lead
them to discuss the fact that, like fish, there are a limited number of beads, and like fish,
they can only increase at a limited rate. Discuss ways in which people might protect the
fish while still being able to use them for food. The two obvious solutions are to give each
person a group of fish to manage as they see fit, or to set up rules that allow anyone to
fish, but limit the number of fish that can be caught. Tell students that these options will be
tested in the next two games.
6. In the next round of play, each student will get a smaller fraction of the beads to manage
as he or she sees fit. Each student should get a plate containing 25 beads. The same rules
apply. After students have had a few minutes to think of a strategy, have them play five
rounds of the game again. Make sure a different student is the recorder than the first time.
Have the recorder record the results of the game on the handout, and record the strategy
of each student.
7. In the next round, all students will again draw from the same group of beads. However, in
this round, students will develop a set of rules to define how many beads each person can
take at each round. Have each group discuss what rules, if any, they will impose on the next
round of play. Remind students that their goal is to allow the people in the group to get as
many beads as possible without the group running out of beads. Each group should write
down their agreed-upon ideas on the handout. Students can even go so far as to make
“laws” of their own to punish people in their group who break the rules established by the
group. Once students have devised a set of rules, have them play another five rounds. The
recorder should be a different student from the first two games. Have the recorder record
the results of the game on the handout.
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STEPS FOR
TRAGEDY OF THE COMMONS
(CONT)
8. Wrap-Up Activity: Lead the class in a guided discussion of this activity. Encourage
groups to share the results of each game they played. Ask guiding questions to help
students focus on the important results. Examples of such questions include the following:
•
•
•
Which strategies helped your group still have beads left
over at the end of the game?
Which strategies helped the members of your group get
the largest number of rewards?
Was it possible for everyone in your group to get the maximum
number of rewards without the group running out of beads?
This activity is somewhat abstract, so using real examples of the tragedy of the commons
is vital to helping students to understand. Remind students that they already discussed
one real example: fish. Have students think of other examples, such as fresh air and fresh
water. Discuss an example with them. For example, have them imagine that they own a
factory that produces paper. Producing paper requires a large amount of water. Have them
imagine that they pump water from a nearby river to use in their factory. They pump so
much water from the river that the amount of water in the river decreases significantly.
Farmers, homeowners, and towns downstream of the factory do not have enough water
for their crops and homes. Ask students whether they would reduce the amount of water
their factory uses, even though it would mean that they would produce less paper (and
therefore make less money). Most students will probably reply that they would reduce their
paper production. Explain that most businesses would probably not choose this course of
action unless laws forced them to. Tell students that this is why it is called the Tragedy of
the Commons. The tragedy is that without rules, those who do not overuse the resource
lose the most, while those who destroy more of the resource gain the most.
Tragedy of the Commons Extension Activity
Students who are interested should be encouraged to try different strategies to find one
that is optimal. The optimal theory in this particular game is for the students to take the
minimum in each of the first four rounds (10 beads) and then take as many as possible in
the last round. Of course, in real life, you would want the resource to continue to be used
indefinitely. Have interested students play longer games, specifying that after each round
there have to be enough beads so that there are never too few beads for anyone. In this
infinite game the optimal strategy for a three-player game is to leave a total of 60 beads
after each round. That will allow each player to get enough beads to get a reward and
continue to the next round, and also allow for another 60 beads in the next round.
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TRAGEDY
OF THE COMMONS
IMPACT!
BACKGROUND
INFORMATION
BACKGROUND INFORMATION
What is the tragedy of the
commons?
What can be done about the tragedy
of the commons?
In the past, many towns had commons, or areas in
town where townspeople could allow their animals
to graze. In 1968, a scientist named Garrett Hardin
published a paper describing how it was
inevitable that common but limited resources,
such as fresh grass for grazing, would be overused
by people who could profit from them. In the
grazing example, each farmer gained more money
for each sheep he could raise on the commons.
This led farmers to put as many sheep as they
could afford onto the commons. However, this
lead to a rapid decline in the number of sheep the
commons could actually feed. Eventually all of the
grass disappeared, and none of the farmers could
support their sheep. Farmers with one sheep and
farmers with 20 sheep were equally unable to feed
their sheep. However, a farmer with 20 sheep—
who contributed more to the destruction of the
commons than a farmer with fewer sheep—made
more profit than a farmer with fewer sheep. This
is why it is called a tragedy: because those who
have the foresight to try to preserve the common
resource lose the most, while those who most
actively destroy the resource gain the most.
There are generally two accepted solutions to the
tragedy of the commons. The first is to make the
resource a private commodity instead of a common
one. For example, if a farmer owned a plot of land that
no one else could graze their sheep on, the farmer
could determine what the best strategy is for use of
that land, without fearing that they would lose out on
potential profits.
The second solution is to regulate the use of the
commons. This solution would allow farmers only a
limited number of animals on the commons. The
farmer that used the commons the most would still
gain more than the farmer who used it the least, but
if the commons was managed properly the amount
of grass eaten by the animals would be equal to the
amount that could grow during that time.
What are some modern examples of the tragedy of the commons?
There are many examples of the tragedy of the commons. Fishing and whaling are common examples, since
the oceans and their contents are common resources. To combat overfishing, nations enact rules allowing
only a certain number of fish to be caught during a certain period of time. International agreements govern
areas of the ocean that are outside the borders of a nation.
Air and water pollution are also examples of the tragedy of the commons. In these examples, fresh water and
clean air are the finite resources. The polluter uses them by dumping the pollution into the water or air.
If there are no rules against such action, then it is more profitable to pollute than to clean up the pollution.
The population in general pays for the pollution, while the polluter derives more profit from each widget he
or she makes, and therefore pollutes more. Efforts to curtail pollution usually entail limiting the amount of
pollution the polluter can put into the water or air. In essence, the government gives out an allowance of
fresh air or fresh water that the polluter is allowed to destroy, much as the government might give a certain
fisherman a given fishing ground to do as he sees fit.
Key Vocabulary:
simulation: a simplified model of a real world situation
Tragedy of the Commons: a situation in which the profitability
of a limited resource leads people to overuse the resource instead
of conserving it
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STUDENT HANDOUT FOR
TRAGEDY OF THE COMMONS
Name
Date
Game 1 results
Players__________________________________________________
Player 1
Player 2
Player 3
Round 1
Round 2
Round 3
Round 4
Round 5
What was your strategy for this round of the game?
Player 1:
Player 2:
Player 3:
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STUDENT HANDOUT FOR
TRAGEDY OF THE COMMONS
Name
Date
Game 2 results
Players__________________________________________________
Player 1
Player 2
Player 3
Round 1
Round 2
Round 3
Round 4
Round 5
What was your strategy for this round of the game?
Player 1:
Player 2:
Player 3:
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STUDENT HANDOUT FOR
TRAGEDY OF THE COMMONS
Name
Date
Game 3 results
Players__________________________________________________
Player 1
Player 2
Player 3
Round 1
Round 2
Round 3
Round 4
Round 5
What was your strategy for this round of the game?
Group:
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