Name: _______________________
Science 1
Tragedy of the Commons Activity
Introduction: A “commons” refers to the natural resources accessible (not owned) by all members of a
society. Examples include forests, rivers, fisheries, grazing land, atmosphere, or other shared resources
that are used and enjoyed by all. In this activity you will learn what can happen to a common resource
that is or is not used sustainably.
Part I: Diverse Fisheries
Materials:
 20 goldfish per group (5 of each color (species): green, red, orange and yellow)
 1 dish per group (lake)
 2 flexible straws (fishing pole) per student
Procedure:
1. Form a team of four students. Each of you represents the head of a hungry family. In order for
your family to survive, you must catch enough fish (and make enough money) for them to eat.
The only food source is a small local lake which can hold up to 20 fish.
2. Once a year you will get a chance to fish (with a straw fishing pole) and each year you may take
as many fish as you want. The fish are worth the following dollar amounts:
a. Green Fish = $5.00 each
b. Red Fish = $4.00 each
c. Orange Fish = $3.00 each
d. Yellow Fish = $2.00 each
3. Your livelihood depends on the amount of dollars you earn from your fish:
a. Less than $7.00 = your family starves
b. $7.00 - $13.00 = your family is well fed
c. More than $13.00 = you can sell the extra fish for a profit
4. You will fish for 5 years and after each year of fishing fill in the Results for Part I.
5. Do not talk while fishing and do not begin until the teacher says to start fishing.
6. The fish that are left in your lake will reproduce (double) once a year. Keep the fish that you
“catch” in front of you.
7. If any person has starved, then they cannot fish the next year.
Results:
Year
# of each type of fish in
the lake (after
reproduction)
# of each type of fish
caught by you
(and money earned)
Total # of each type of
fish caught per year
1
2
3
4
Discussion Questions:
1. Did your family survive all four years of fishing? Explain why or why not
2. Was your family able to make extra money? If so, how much?
3. Did anyone in your group take too many fish? If so, what was the consequence?
4. How did it make you feel if other people took too many fish?
5. Was there a fish species (color) that people preferred? How did that affect their population?
6. Did any of the fish go extinct? If so, which and why?
7. Did everyone in your group try to take as many as possible? Why or why not?
8. Does our society reward those with the “most”? How?
9. Did anyone sacrifice the number of fish they caught (catch less) for the good of the community?
Why or why not?
10. Does society ever reward that type of person? Why or why not?
11. Think of a local “commons” that you are familiar with (public bathrooms, parking lots, school
cafeteria, hallway, etc.). Do similar situations arise in those areas? Explain.
12. What are some other natural resources (besides fish in a lake) that are “common” resources?
13. If you were to participate in this simulation again, would you change your approach? How and
why?
Part II: Non-Diverse Fisheries
Materials:
 20 goldfish per group (all one species – yellow)
 1 dish per group (lake)
 1 to 2 flexible straws (fishing pole) per student
Procedure:
1. Form a team of four students. Each of you represents the head of a hungry family. In order for
your family to survive, you must catch enough fish (and make enough money) for them to eat.
The only food source is a small local lake which can hold up to 20 fish.
2. Once a year you will get a chance to fish (with a straw fishing pole) and each year you may take
as many fish as you want. The fish are worth the following dollar amounts:
a. Green Fish = $5.00 each
b. Red Fish = $4.00 each
c. Orange Fish = $3.00 each
d. Yellow Fish = $2.00 each
3. Your livelihood depends on the amount of dollars you earn from your fish:
a. Less than $7.00 = your family starves
b. $7.00 - $13.00 = your family is well fed
c. More than $13.00 = you can sell the extra fish for a profit
4. You will fish for 5 years and after each year of fishing fill in the Results for Part II.
5. Do not talk while fishing and do not begin until the teacher says to start fishing.
6. The fish that are left in your lake will reproduce (double) once a year. Keep the fish that you
“catch” in front of you.
7. If any person has starved, then they cannot fish the next year.
Results:
Year
# of each type of fish in
the lake (after
reproduction)
# of each type of fish
caught by you
(and money)
Total # of each type of
fish caught per year
1
2
3
4
Discussion Questions:
1. Did your family survive all five years of fishing? If yes, explain how.
2. Was your family able to make extra money? If so, how much?
3. Did anyone in your group take too many fish? If so, what was the consequence?
4. Did anyone sacrifice the number of fish they caught (catch less) for the good of the community?
Why or why not?
5. How did this fishing simulation compare/contrast to the first simulation (with a diverse fish
population)
6. If you were to participate in this simulation again, would you change your approach? How and
why?
Part III: Polluted Fisheries
Materials:
 16 colored goldfish per group (4 of each color (species): green, red, orange and yellow)
 4 pretzel goldfish (polluted fish)
 1 dish per group (lake)
 1 to 2 flexible straws (fishing pole) per student
Procedure:
1. Form a team of four students. Each of you represents the head of a hungry family. In order for
your family to survive, you must catch enough fish (and make enough money) for them to eat.
The only food source is a small local lake which can hold up to 20 fish. However, a pollutant
has entered the lake and caused some of the fish (pretzel fish) to get sick. If your family eats or
sells any of these fish, you have to pay for medicine.
2. Once a year you will get a chance to fish (with a straw fishing pole) and each year you may take
as many fish as you want. The fish are worth the following dollar amounts:
a. Green Fish = $5.00 each
b. Red Fish = $4.00 each
c. Orange Fish = $3.00 each
d. Yellow Fish = $2.00 each
e. Pretzel Fish = -$5.00 each (your family gets sick and has to pay for medicine)
3. Your livelihood depends on the amount of dollars you earn from your fish:
a. Less than $7.00 = your family starves
b. $7.00 - $13.00 = your family is well fed
c. More than $13.00 = you can sell the extra fish for a profit
4. You will fish for 5 years and after each year of fishing fill in the Results for Part III.
5. Do not talk while fishing and do not begin until the teacher says to start fishing.
6. The fish that are left in your lake will reproduce (double) once a year. Keep the fish that you
“catch” in front of you.
7. If any person has starved, then they cannot fish the next year.
Results:
Year
# of each type of fish in
the lake (after
reproduction)
# of each type of fish
caught by you
(and money earned)
Total # of each type of
fish caught per year
1
2
3
4
Discussion Questions:
1. Did anyone in your group catch polluted fish? If so, what were the consequences?
2. Did your family survive all five years of fishing? If yes, explain how.
3. Was your family able to make extra money? If so, how much?
4. Did anyone in your group take too many fish? If so, what was the consequence?
5. Did anyone sacrifice the number of fish they caught (catch less) for the good of the community?
Why or why not?
6. How did this fishing simulation compare/contrast to the first simulation (with a diverse fish
population)
7. What are some examples of pollution that could harm fish?
Part IV: Technology and Fisheries
Materials:
 20 colored goldfish per group (5 of each color (species): green, red, orange and yellow)
 1 dish per group (lake)
 1 spoon (fishing pole) per student
Procedure:
1. Form a team of four students. Each of you represents the head of a hungry family. In order for
your family to survive, you must catch enough fish (and make enough money) for them to eat.
The only food source is a small local lake which can hold up to 20 fish. You have learned about
new technology which will help you catch more fish.
2. Once a year you will get a chance to fish (with the new technology) and each year you may take
as many fish as you want. The fish are worth the following dollar amounts:
a. Green Fish = $5.00 each
b. Red Fish = $4.00 each
c. Orange Fish = $3.00 each
d. Yellow Fish = $2.00 each
3. Your livelihood depends on the amount of dollars you earn from your fish:
a. Less than $7.00 = your family starves
b. $7.00 - $13.00 = your family is well fed
c. More than $13.00 = you can sell the extra fish for a profit
4. You will fish for 5 years and after each year of fishing fill in the Results for Part IV.
5. Do not talk while fishing and do not begin until the teacher says to start fishing.
6. The fish that are left in your lake will reproduce (double) once a year. Keep the fish that you
“catch” in front of you.
7. If any person has starved, then they cannot fish the next year.
Results:
Year
# of each type of fish in
the lake (after
reproduction)
# of each type of fish
caught by you
(and money earned)
Total # of each type of
fish caught per year
1
2
3
4
Discussion Questions:
1. Did your family survive all five years of fishing? If yes, explain how.
2. Was your family able to make extra money? If so, how much?
3. Did anyone in your group take too many fish or more than one fish at a time? If so, what was the
consequence?
4. Did anyone sacrifice the number of fish they caught (catch less) for the good of the community?
Why or why not?
5. How did this fishing simulation compare/contrast to the first three simulations (diverse, not
diverse, and polluted fish populations)?
6. How did technology affect the amount of fish each family caught?
7. What are some examples of technology in the real world that allow fishermen to catch more fish?
Part V: Sustainable Fisheries
Materials:
 20 goldfish per group (5 of each color (species): green, red, orange and yellow)
 1 dish per group (lake)
 2 flexible straws or spoon (fishing pole) per student
Procedure:
1. Form a team of four students. Each of you represents the head of a hungry family. In order for
your family to survive, you must catch enough fish (and make enough money) for them to eat.
The only food source is a small local lake which can hold up to 20 fish.
2. Before this round of fishing your group needs to discuss how all families can survive while
ensuring the future of the fish population. Basically, you must figure out how to fish
sustainably.
3. Once a year you will get a chance to fish (with a straw fishing pole or spoon) and each year you
may take as many fish as you want. The fish are worth the following dollar amounts:
a. Green Fish = $5.00 each
b. Red Fish = $4.00 each
c. Orange Fish = $3.00 each
d. Yellow Fish = $2.00 each
4. Your livelihood depends on the amount of dollars you earn from your fish:
a. Less than $7.00 = your family starves
b. $7.00 - $13.00 = your family is well fed
c. More than $13.00 = you can sell the extra fish for a profit
5. You will fish for 5 years and after each year of fishing fill in the Results for Part V.
6. During this round of fishing you may talk with the other fishermen. Do not begin until the
teacher says to start fishing.
7. The fish that are left in your lake will reproduce (double) once a year. Keep the fish that you
“catch” in front of you.
8. If any person has starved, then they cannot fish the next year.
Results:
Year
# of each type of fish in
the lake (after
reproduction)
# of each type of fish
caught by you
(and money earned)
Total # of each type of
fish caught per year
1
2
3
4
Discussion Questions:
1. Were all of the families able to survive for all five years? If yes, explain how.
2. Were any of the families able to make extra money? If so, how much?
3. Is it possible to maximize the number of fish caught per person and the number of fish remaining
in the lake? Explain how.
4. How did this fishing simulation compare/contrast to the first four simulations (diverse, not
diverse, and polluted, technology fish populations)?
5. What are global commons? Give some examples. Are they being used sustainably? Explain
why or why not.
6. What can people do to use these commons (resources) more wisely?
Adapted from earthwatch.org “Go Fish”