All rocks are one of three basic types - igneous, sedimentary, or metamorphic. Even though these words sound complicated, it is really pretty easy to see what they mean, by modeling what happens when different types of rocks are formed. And, even though we could do that with clay or playdough, it is much more fun to do it with something we can eat! Let’s make some chocolate rocks!
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what you'll need
All rocks on Earth are made in one of these three ways - either by melted rock cooling (igneous), by pieces of broken rocks being compressed together (sedimentary), or by rocks being compressed and heated (metamorphic). This is called the rock cycle, because a rock could start out as an igneous rock, be broken into bits by wind and water, be compressed and turned into a sedimentary rock, then be buried deep underground by an earthquake or other natural disaster, and then be changed into a metamorphic rock. Scientists called geologists study the different types of rocks and can tell, just by looking at a rock, if it is igneous, sedimentary, or metamorphic, based on how it looks and where it is found.
variations and related activities
Since the rock cycle takes millions of years, it is much easier to model it with other things, rather than using real rocks! Here are some other ways to understand the rock cycle and how it works.
This experiment is adapted from an experiment that we posted on our Facebook page July 17. Here is the link to the original, from the Fernbank Museum: https://youtu.be/7UDjqOe9arU
Here’s one that uses crayons: https://littlebinsforlittlehands.com/crayon-rock-cycle
Here’s another one, using Starburst candy. Notice - this one needs adult help, because it involves melting the candy: https://lemonlimeadventures.com/edible-rock-cycle-for-kids/
This one uses either grated chocolate, or grated crayons (don’t do both together!): https://www.mos.org/sites/dev-elvis.mos.org/files/docs/education/mos_geology-rock-detectives_diy-rock-cycle.pdf
references and links to more information
This article has simple, kid-friendly language about rocks and how they form: https://www.ducksters.com/science/rocks.php
This article, from National Geographic, is very clear and concise. [NOTE: You might have to sign up for a free National Geographic membership to view this one]: https://www.nationalgeographic.com/science/earth/inside-the-earth/rocks/
If you’d like to jazz it up, here is the same information in a rap song: https://youtu.be/G7xFfezsJ1s
The Colorado School of Mines in Golden has a very cool museum, which teaches about geology in a number of neat ways. Of course, they are closed right now, but they do have kits which are available for checkout, if you want to learn more! Check it out here: https://www.mines.edu/museumofearthscience/
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