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Lab 2
The Tragedy of the Commons: A Classroom Simulation Exercise
Description of the Lab
This laboratory exercise is a simulation of the problem of the “tragedy of the commons” which occurs when overpopulation leads to the overconsumption of a common resource. Students will role play as members of a family living in a rural, undeveloped village and living off of the land. Small, wrapped candies represent the common food resource and students will, as part of a family unit, make decisions about how much resource they will use and how quickly they will use it. The same student groups will attempt to control the depletion of the resource through a system of private ownership as well as a number of regulatory systems.
Outline of Investigation
This lab simulation exercise has four different parts, each modeling a different system of common resource use under high population conditions. The instructor can use any combination of these parts.
- Part 1 models uncontrolled common resource use.
- Part 2 models uncontrolled common resource use combined with private ownership of resource.
- Part 3 models common resource use controlled by internal regulation.
- Part 4 models common resource use controlled by external regulation.
- Students are placed in groups of 4-6 representing a family. Each family is given a cup for holding ‘fish’ (candies).
- Based on the specific rules for each scenario, one member of each team ‘fishes’ for ‘fish’.
- Teams record their ‘catch’ on the data sheet while the instructor replaces the fish taken using a doubling reproduction scheme.
- Teams continue to fish until a) all fish are gone or b) instructor has them stop.
- Teams answer questions about the factors that influenced their fishing methods.
- Steps 2-5 are repeated using different scenarios for resource regulation (Parts 2-4).
Laboratory Materials and Equipment for Student Use
Ideally, students will be put into groups of 3 or 4. Five is the limit and should be reserved for placing odd numbers of students.
Materials and Equipment / Per Student / Per Pair / Per Team / Per RoomSmall wrapped candies (i.e. Starburst) / 10
Medium size dark plastic cup / 1
Small size dark plastic cup / 1
Plastic spoon (Part IV only) / 1
Prewritten Permits and Seasonal Limit Signs (Part IV only) / 1
Preparation of Laboratory Materials and Reagents
If there are an odd number of students for groups, or if the class is exceptionally large (greater than 30 students), the instructor might find it easier to choose one or two students to help with the scattering and reproduction of the candy resource during this simulation.
Part1:
- Before students enter the classroom, hide/scatter exactly 4 pieces of the wrapped candy for every student group. For example, if you have a class of 20 students divided into five groups of four students, hide 5 x 4 or 20 pieces of candy. This represents the carrying capacity of the land.
- After the groups finish their one minute hunting session, go to each group and count how many candies they have taken. Use this number to determine how many candies were left. Scatter the same number of candies prior to the start of the second round (in other words, reproduction occurs by doubling the number left). Remember that you can never go over the original number of hidden candies – this represents the carrying capacity of the land. For example, if you originally hide 20 candies and the groups take 16 candies, you would have 4 candies remaining hidden and you would add 4 MORE candies to make 8 total prior to the start of round two.
Part 2:
- Follow the same set-up and procedure for Part 1. Commons hunting will follow the same rules as stated above.
- Each group will now have a small plastic cup containing four candies. After each round of fishing, after you reproduce the commons land, you will reproduce the private land at the same rate (doubling) as the commons with the maximum number of candies in the private land always at 4.
Part 3:
- Set-up and procedure is exactly the same as for Part 2.
Part 4:
The instructor may choose to forego the use of the private land resource in part 4 in order to shorten the lab time.
Technological Regulations:
Set-up and procedure is exactly the same as for part 1 or 2 EXCEPT all candy collecting must be done using a plastic spoon to pick up the candies. This should significantly limit the number that can be taken in one minute. Remember that only one person can hunt and candies can never be touched by hands, which means that after 1-2 candies are picked up, they must be carried over to the large plastic cup and dropped off before more can be picked up.
Seasonal Limits:
Set-up and procedure is exactly the same as for part 1 or 2 EXCEPT the instructor will post a SIGN that states the legal hunting LIMIT for the time of year. After each round, the instructor will check the numbers of candies taken. Any family that takes more than the posted limit will be fined in a pre-determined manner. Suggestions for fines: taking all remaining candies, forbidding hunting in future rounds, cash payment (25 cents per extra candy is a good ‘fine’).
Permit Based Cap and Trade Regulation:
Set-up and procedure is exactly the same as for part 1 or 2 EXCEPT the instructor will pre-prepare specific permits and hand them out to all families. Permits will state:
- Number of candies that may be taken per hunting period.
- Maximum number of candies that can be taken in any one round by any permit holder. (for example, a permit might state permission to collect 3 candies, but the maximum number of candies that can be taken per round might be 10 candies – if a family can buy/trade to get more than one permit to pick up candy, the maximum number allowed would be 10 regardless of how many permits they hold.)