In My Classroom: Investigating Energy Flow with ZOMBIES!

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Welcome to the KABT blog segment, “In My Classroom”. This is a segment that will post about every two weeks from a different member. In 250 words or less, share one thing that you are currently doing in your classroom. That’s it.

The idea is that we all do cool stuff in our rooms and to some people there have been cool things so long that it feels like they are old news. However, there are new teachers that may be hearing things for the first time and veterans that benefit from reminders. So let’s share things, new and old alike. When you’re tagged you have two weeks to post the next entry. Your established staple of a lab or idea might be just what someone needs. So be brief, be timely and share it out! Here we go:

Investigating Energy Flow with ZOMBIES!

studentwork

The Set-Up

It’s the zombie apocalypse! You have a safe fenced-in area that is impenetrable to the zombies.  But, you also cannot leave the fenced in area. If you had time to prepare this land, what would you plant? What livestock would you have? (Note: Students have the option of doing a Mars Biodome if they do not want to do the zombie apocalypse.)

Student groups are all given the same 11 x 17 inch grid paper. Each square equals 100 square feet. Each student needs a housing structure(s) that equal 20×25 squares.

grid

The Goal

Sustain as many humans as possible using the land space given. The group who can sustain the highest number of people wins. The criteria for sustainability is 2,000 calories per day, per adult (730,000 calories per year). (Note: No stockpiling allowed).

The Work

Students need to find the total number of producer calories from all their crops. (Find the calories / square foot for each food, and then multiple by the number of total square feet.)

corn

Then, students need to calculate how many of those producer calories are actually available for human consumption. To do so, students must figuring out how many of those producer calories their livestock will consume per year.

plant-cal-conversion

The only livestock here was goats, if you have different species of livestock you’ll want to add those together to do this calculation.

Next, students need to find the total number of anaimal calories produced. They calculate how many calories of meat (or eggs/dairy) each animal produces. (To simplify, one could assume the entire weight of the animal is meat.) Students do this for each type of livestock and add it together to find the total number of livestock calories produced. (If you have any secondary consumers, they will take a whole other set of calculations!)

Next, students find out how many calories their land produced for human consumption. They take the number of plant calories available for humans and add it to the total number of animal calories produced. Then, they divide that by 730,000 (the total number of calories needed per human per year) to see how many humans they can support.

1865

Getting the Numbers

To make it easier, you could provide a list of several crop and livestock options with their calorie information. But, for me, one of the best parts of this project was having it open ended for the students. I have my students find the information on their own, but they have to back it up with a credible source. This gets pretty competitive, so the students really hold each other accountable.

Discussions

Here are some important questions that we discussed after completing this project:

Goat image from Microsoft clip art

Goat image from Microsoft clip art

  1. Why do we lose calories when we feed them to livestock?
  2. What is the “best” crop? (calories vs. nutrients)
  3. Should we be putting plant calories into livestock?
  4. What are the pros and cons of having livestock?
  5. What would be the “best” livestock? (For example, for many reasons crickets are much more energy efficient than cows.)
  6. What does this make believe scenario have to do with the real world?

Tips and Suggestions

I suggest you have a running list of “rules” that you as a group decide upon throughout the project. For instance, someone will probably ask if it’s okay to do a rooftop garden. Whatever you decide, you should keep documentation of the “rules” your class makes. The students get pretty competitive and this is helpful.

To simplify our model, we assumed a lot. 1) People only need calories to survive, not certain nutrients. 2) We have sufficient water, fertilizer, and everything else needed to grow the crops. 3) We can store crops up to one year, and there is no limit to the type of crops that can be planted due to climate, etc. 4) Animals can only eat the part of the plant that humans eat. 5) All animals reproduce each year. 6) We eat the entire weight of the animal in meat. And more. But, these assumptions lead to fantastic discussions! I have students write about them for part of the end paper. They are also great opportunities for extensions.

Even with all of the assumptions and simplifications, the students were really able to “get it” in terms of energy transfer and the 10% rule.

If you’d like a more detailed description or have any questions, please e-mail me. jesirhodes@gmail.com

I know KELLY KLUTHE has some cool stuff to share! Tag, you’re it!

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