Chocolate Rock Cycle Activity

I really like to do this activity with chocolate when teaching the Rock Cycle—it's such a great hands-on summation of how each step of the process works. You can see more pictures and instructions here from last time we did it. But, since this is also a journal for our family, I'm going to post pictures and a brief summary from this time too.

(It's interesting to compare the pictures of Malachi doing this activity…six years apart!)

Start with several types of baking chips for each child. We had chocolate, peanut butter, and white chocolate chips. These are your basic rocks and minerals. Let the children "weather" some of their rocks by grating them into smaller pieces with the microplane grater and letting the pieces fall on the aluminum foil.

Next, fold the foil into a packet and squish the little pieces and big pieces all together inside. Add lots of pressure—my kids like to step on and sit on their packets to make everything stick together.

When they unwrap their foil packets, they can see that all the different rocks and minerals have been cemented together into a "sedimentary rock"!

Next, wrap your rock up in foil again and add even more heat and pressure! Flatten it with your fist as hard as you can, stomp on it, hold it for a long time between your palms, pile books on top of it—whatever you can think of.

And the sedimentary rock has become a metamorphic rock! Notice that the discrete sediments have fused into larger swirled or marbled patterns.

(Note: The Metamorphic Snickers Bar activity is fun one to go along with this topic, too.)

Finally, seal up your metamorphic rock in the foil and put it into a pan of hot or boiling water. Let it sit for a minute or two, then carefully unwrap it and swirl the rocks and minerals around with a toothpick or a fork. You can see that all the different minerals have melted and formed a much more homogenous mass (though it still contains all the same ingredients!).

This is your igneous rock! And, you could "weather" all the different rocks into pieces and start the process all over again!

Or you could just let the children eat their "igneous rocks." :)

When we were done, the children all drew illustrations of the rock cycle to demonstrate their understanding of the principles. Some of them used…leaves?

Nice genuine smile, Junie. :)

Chocolate Rock Cycle

Now, to put all this information together in the Rock Cycle! There are lots of ideas online about how to simulate the rock cycle. You can use crayon shavings, but we used three types of baking chips---chocolate chips, peanut butter chips, and white chocolate chips.

You can start the cycle at any point. We started by "weathering" various rocks and minerals (the baking chips) into smaller sediment. We used graters, paring knives, and a microplane grater to do the weathering. You want some very small pieces, and some larger pieces, of each type of baking chip.

Sprinkle a little bit of each type of sediment onto a piece of foil. Wrap it up tight and then add some pressure. You can squeeze it tightly between your hands (this adds a bit of heat) and then stand on it. Put a book on top to distribute your weight evenly.

Unwrap the foil to see your sedimentary rock! Each person's "rock" will be a bit different, based on the rocks and minerals that it is composed of. Be careful when handling these rocks because they are quite fragile.

Now add more heat and pressure to make a metamorphic rock. We re-wrapped our rocks tightly in the foil and then floated them on some hot water for 10 seconds or so. (You don't want to melt the chocolate completely.) Press the foil between your hands again to add more pressure. Then put the rock (in its foil packet) into the refrigerator to harden for several eons (10 minutes or so). :)  Unwrap it to see your metamorphic rock! You can observe, at this point, that some of the "minerals" making up the rock are more melted and disfigured than others. This is true to nature, as different minerals have different melting points and will also re-crystallize at different temperatures.

Igneous rocks are next. Take your metamorphic rock, re-wrap it in foil, and float it for a longer time on some hot (even boiling) water.

Sometimes a little bit of water leaked into our foil "boats." It's okay.

Unwrap, take a toothpick, and stir the melted rock and minerals around. This is "magma," and you are creating convection currents in it.

Refrigerate the rock again until it's hard. Now you have an igneous rock! The minerals are still present, but you can no longer see them as individual components because they all melted together in the magma.

We LOVED this activity. It is simple and yet it models the process so well!

Sebastian's illustration of the rock cycle