What is the Rock Cycle?

Rock cycle hands on activities for the elementary classroom, including a song and video explanation. 

Teaching kids how rocks can change into other types is a messy business because it can be really confusing.

When I moved to third grade so many years ago, I found myself having to learn about the rock cycle.  I was surprised that it is really interesting, and it quickly became one of my favorite geology lesson plans.

But here was the bad part:  I made it too complicated the first time I taught it. 

Have you ever done that?  Of course you have!  As with most difficult concepts, we learn that the simpler we make it, add a song and a story (maybe throw in some art) and these difficult concepts become super-easy to understand.

Simple explanation:  The rock cycle is when different types of rocks break down, change and are made into new types of rocks.  Like the water cycle, it is ongoing and all rocks are somewhere in the cycle (always).

Ok, but having this make sense to kids is another thing.  We have to teach them in ways they understand.  So here are two of my favorite tips for explaining the rock cycle to elementary students.  Feel free to jack them up and use them anyway you can!

The Rock Cycle Song

This igneous, metamorphic, sedimentary rock song is to the tune of “Row Row Row Your Boat”:

SEDIMENTARY rock has been formed in layers.
Often found near water sources – fossils from decayers.

Then there’s IGNEOUS rock, here since Earth was born.
Molten lava, cool and hard – that is how it’s formed.

These two types of rocks can also be transformed.
Pressure, heat and chemicals – METAMORPHIC they become.

The video below is a super-cute one to show to the class.  Some really good explanations of the different types of rocks are included in it, along with answering, “What is the rock cycle?”

Rock Cycle Experiment

While this may not be the most “scientific,” it certainly makes understanding what happens during the cycle easy to understand. 

Plan for a few days and collect quite a few crayons before doing this.  Depending on the age of your students, you may want to keep it as a demonstration only.

Materials:

  • 5-10 different colored crayons, shredded (keep the colors separate; a cheese grater works well)
  • Aluminum foil
  • Hair dryer
  • Heavy books
  • Metal tongs
  • Candle and matches


Step One

The crayon shavings represent sediments.  Place them layers, one on top of the other, in the foil and wrap them up like a burrito so nothing will fall out. Press on them with your hand and explain how the layers build up over time and they end up joining together.  It will chip easily and this can be demonstrated by showing the students how the crayon shreds can be pulled apart.

Teacher Tip:  We find sediments in water, such as rivers.  Sedimentary rock is a mixture of minerals, dirt, sand, and organic matter that has settled at the bottom of the water.  These layers eventually become so heavy that the sediments (or ingredients) form sedimentary rock.  You will be able to easily see bands or layers in most of these types of rocks.

To better understand this concept, you should have your students make some Yummy Sediments!



Step Two

Turn the hair dryer on and gradually heat up the foil packet (this will actually make for a prettier demonstration if you do this).  Then place 4-5 heavy books on top of the foil wrap and explain to the students that the sediments have to be under a lot of pressure and/or heat to turn into another type of rock: metamorphic. 

Let the wrap stay under the books at least overnight to demonstrate that it takes a long time to change.

The next day, unwrap the foil and show the students how the sediments have been pressed together, making a special note about seeing the different layers of colors but now it cannot be pulled apart like before.

Teacher Tip:  Metamorphic rocks are harder and much smoother than sedimentary rocks.  They have crystals and can only form from existing rocks (either sedimentary or igneous).


Step Three

You may want to try rolling some of the “metamorphic rock” into a small ball for this, but be sure to wrap it up into some more foil.

Using the metal tongs, hold foil packet(s) over a lit candle.  This will heat up the packet quite a bit so you will also need a plate or tray to put it on as it cools.  After it has cooled, unwrap it to show how it is now igneous rock.

Teacher Tip:  Igneous rocks are made when magma (molten rock under the earth’s surface) is pushed into the higher layers of the crust where it cools and solidifies.  Slow cooling forms large crystals and fast cooling makes smaller ones.