Teaching Earth Science with Food - Layers of Earth and Plate Tectonics

A month or two ago when we started our Earth science unit, we started with reviewing the layers of the Earth and plate tectonics. For science, we generally devote a day of the week to reading, videos, and discussion, and a separate day for demonstrations or experiments. I especially love when I can find or come up with edible demonstrations, since we then get a treat out of it as well. I was delighted when I found two sugary-sweet treat demonstrations that could be combined to discuss our subject.

A big thanks to the American Museum of Natural History and the Red Cross Blog for the inspiration! Make sure to check out their links for more detailed explanations of the science (and not just the yummy food) part of this. All I did was combine the ideas and minorly adjust a couple things that didn't work out as well for us.

And now - Ooey, Gooey, Edible Earth! - A lesson in Earth structure and plate tectonics.

(Please excuse the especially low quality photos. I took these hastily with a cell phone camera, not realizing I would later want to share the demonstration.)

Ingredients:

1 gumdrop
1 large marshmallow (left intact)
2 c rice krispy cereal
1 T butter
13 large marshmallows (for melting)
1 tsp shortening or butter for greasing
1 can chocolate frosting
at least 4 cream-filled sandwich cookies

Instructions:

1. Inner and Outer Core - Use your fingers to poke a little hole into a large marshmallow. Push the gumdrop into the marshmallow and squish the marshmallow around so the gumdrop is surrounded by marshmallow. Set aside.

2. Lower Mantle - Lightly grease or use cooking spray on the inside of a large glass bowl. Place a piece of waxed paper on your workspace. Add the butter and the remaining 13 marshmallows to the bowl. Microwave for 30 seconds, then stir and microwave for an additional 30 seconds. Quickly add the rice krispies to the melted mix and stir completely. Keep stirring while the mixture cools slightly. Meanwhile, have student coat hands with shortening or additional butter. While still warm, but cool enough to handle, roll the rice krispy mixture around the prepared core marshmallow.

The wax paper is to protect your work surface from inevitable marshmallow goo droppings.

3. Asthenosphere - Once your rice krispy mantle is packed around the core, dip into the frosting and start spreading. Cover the entire earth in a layer of frosting.

This lasted about 30 seconds before they asked me to take over spreading.

4. Lithosphere - Separate your sandwich cookies and place the cream side down in the frosting. They are not going to lay quite flat, of course. It's okay if they break a bit.

You could coat the whole thing in cookie, but we decided this was sugary enough.

5. Plate Boundaries - First, show how the cookies are like the tectonic plates. They slide over the asthenosphere. Remind the student that the plates move around in different ways, producing different changes on the surface of Earth.

-Divergent plate boundary - Move two plates apart. If you do the demonstration with a little pressure, your student can see the asthenosphere moosh up (that is the scientific term, I'm sure) from the opening between the plates.

-Convergent plate boundary - Push two plates together, with one going under the other. Check out the subduction zone.

-Transform plate boundary - Slide two plates past each other. This works best if you have two broken cookies with jagged edges that kind of grab each other, so you can really feel and hear the "earthquake" when those edges break loose and slide.

Can you find all the plate boundaries here?

6. Examine the layers - Now that your Earth is assembled, cut it open. You can talk about the properties of the different layers - the solid inner core; the hot, liquid outer core; the hard but slightly flowing lower mantle; the viscous, slowly flowing asthenosphere; and the rigid lithosphere.

Lastly, you can eat it!

Can you see the eyes lighting up with sugar?

Just don't eat it all in one go. The exact nutrition facts will of course depend on what kind of cookies and frosting you're using, and how much of each, but I'm coming up with a minimum calorie count around 1300 for the whole Earth model, and over 100 grams of sugar. More than just a tiny piece will make you feel quite ill (ask me how I know..).