The Tragedy of the Commons!


Today, students learned all about populations. We began by discussing world population and how it has increased from 1 billion to 7 billion people in just over 200 years. Students correctly identified China (1.3 billion) and India (1.2 billion) as the most populous countries in the world.

Students learned about two major concepts in population ecology – carrying capacity and the Tragedy of the Commons.  Carrying capacity is the maximum number of individuals that an area can support without exhausting or depleting the available resources.

The first 8th grade class got to learn the role of a population biologist when they estimate the levels of the population.  Students got to work on the Wild Beans (Mark and Recapture) activity.  Here, students were given a bag filed with ‘wild’ white beans and they had to estimate the level of the population by capturing a sample of the population and replacing the white beans with red beans to indicate they have been marked.  After students gathered this data, they had to estimate the level of the population and identify the percent error involved in this procedure.  Students learned that this is what population biologists focus on to be able to understand and monitor populations on Earth.   

The second 8th grade class explored the Tragedy of the Commons in a game where students grouped together in villages that survived by fishing. Inevitably, villagers who caught the maximum number of fish allowed each year ended up not leaving enough fish in the pond to reproduce to provide food for the next year. Villagers starved and villages collapsed until some students realized that if they fished enough to survive, but not enough to deplete the fish resource, the game could continue indefinitely – or as we say in ecology – sustainably – for many generations.

Additional Information:

We watched a great video about population that you can review here.

Watch this short video to find out more about Tragedy of the Commons.

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