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Upper El (Mr. D): Carrying Capacity and More!

This week we worked on finalizing our Science Fair procedures, so the steps of our experiments are clear. Then we went deep into a science concept called carrying capacity to answer why we are considering bringing human life to other planets?

Last week, students spoke up and asked me why? Why are we thinking about sustaining life on another planet? That's where we started on Monday. First, I asked our group what they thought. Why might it be important to consider that question?

Asteroids! Global Warming!

Sure, these are problems to consider. But, I think there's another way to come at this. I explained a concept called carrying capacity using a theoretical island full of carrots and rabbits. There are a ton of carrots and only a few rabbits. What happens next?

The rabbit population grows!

And what happens to the carrots? Eventually, we reach this point where the rabbit population grows to exceed how many carrots can feed them all. So, some rabbits die—sad face. This allows the carrots to expand in number, and then the rabbits can grow in population again. This point, where the island of carrots can support no more rabbits, is the carrying capacity for rabbits on that island.

This is a pretty deep lesson, so we spent a few minutes making sure we understood it. Then, to the next question: do humans have a carrying capacity on Earth? We might say the obvious answer is, "of course," but I wanted us to think it through thoroughly. What could humans have done on that island that rabbits couldn't?

We can farm! We can make shelter!

Yea! Exactly. We're pretty special. We aren't limited in the same way, but the question is, are we still limited overall? I broke our class into five groups to think a few questions over.

The first was to make a list of two things. What factors help to expand our carrying capacity on Earth? The example we used was farming and agriculture. Then, what factors limit our carrying capacity on Earth? I wanted our class to go beyond just natural resources, so I gave them the thought of war. Wars don't help our population grow!

The second question was to imagine a perfect world—all that we could control was executed perfectly. For instance, since wars are within our collective control, imagine those are gone from our limiting factors. After all of that, do we still have a carrying capacity?

Finally, and the hardest one, whether you think we have a capacity or not, how could we try to calculate it? I didn't want anyone to try to get an actual number but to think about how we might approach getting to one. There is no definitive answer that I could find on this question anywhere. So, maybe Upper El could think of a way to g