Earth History: Crayon Rock Cycle
This activity introduces the 3 main types of rocks and the processes that form them. Wax crayons are eroded into sediment, compacted into sedimentary rock, partially melted and pressed into metamorphic rock, and finally melted and cooled into igneous rock. This understanding is the basis of the rock cycle.
This activity is designed for students to make observations about the 3 types of rock, (igneous, metamorphic & sedimentary) and to discuss the relationships between them. Students will diagram the rock cycle. Given one of the three major types of rock, students will describe the geologic processes that formed it.
The activity calls for the students to work individually, in partners, or small groups to observe & and analyze 3 types of rock samples, record & share their observations. Next, students will be guided through the formation of crayon "rocks" that model the processes that create each of the 3 types of rock. As students work through the models, they complete a diagram of the rock cycle.
- rock cycle
Context for Use
- It is helpful in the discussion of sedimentary rocks if students are familiar with soil separation & identifying different sediments by size. This activity would work nicely after the FOSS Landforms lesson on soil deposition (Investigation 2: part 2).
- You may want to reproduce vocabulary-cut & paste flashcards, which can be downloaded from http://mjksciteachingideas.com/pdf/RockCycleVocab.pdf.
Resource Type: Activities:Classroom Activity
Grade Level: Intermediate (3-5)
Description and Teaching Materials
- describe 3 major types of rock, (sedimentary, metamorphic, and igneous) & discuss the relationships between them
- diagram the rock cycle
- given on the the 3 types of rock, can describe the geologic processes that formed it
Crayon Rock Cycle - Getting Ready
- Rip sheets of aluminum foil into 6 inch squares
- Set out remaining materials
for each student: 1 crayon, knife, cereal-size bowl (doesn't tip as easily as a styrofoam cup), and hot water source, a copy of Rock Cycle Diagram handout
for the class: samples of sedimentary, metamorphic & igneous rock, sorted into boxes of the same rock type and basins to dump the water after it has cooled in the students' bowls.
- Sort the rock samples into the 3 main categories of rocks if they aren't already sorted
(individuals, partners or small groups depending on the # of materials & rock samples you have available)
- Pass around samples of sedimentary rock. Ask students to observe the rocks and describe some of the similarities between them. As students offer their ideas, write them on the board in one column. (**Students may copy the chart into their science notebooks.) You should end up with a list like: 1st rock type: can see grains, grains can be of different sizes, has layers or streaks, grains come off if you rub it.
- Collect the sedimentary rocks and then pass around samples of metamorphic rocks. Ask students to observe the rocks and describe how these rocks are different from the sedimentary rocks. Again, write their ideas in a column on the board. You should end up with a list like: 2nd rock type: no grains, has crystals, many colors, very hard, swirly patterns.
- Collect the metamorphic rocks and then pass around samples of igneous rocks. Ask students to observe the rocks and describe how these rocks are different than the other two types of rocks. Again, write their ideas in a column on the board. You should end up with a list like: 3rd rock type: no grains, some have crystals, some have lots of holes, uniform texture and pattern throughout the rock, no layers or swirls.
- Tell the students that they have been observing and categorizing the 3 major types of rocks: sedimentary, metamorphic, and igneous rocks. Explain that today, they will be using crayons to model the processes that create each of these 3 types of rock.
- Pass out the handout, crayons, foil, and knife.
- Tell students that they have been given a sample of a crayon "rock". Looking at the 3 descriptions on the board, which one is this sample most similar to? It doesn't have grains, layers or streaks. Thus it is an igneous crayon rock! On their handout, in the box at the top of the circle, have students write "igneous rock".
- The first step is to create sediment. Have students unwrap their crayons and then create a pile of crayon shavings on their piece of aluminum foil by scraping it with the knife. They may trade crayons among themselves to acquire a mixture of colors. Give them around 5 minutes to build up a decent sized pile.
- On the diagram, the arrow from "igneous rock" can be labeled "erosion". The next box can be labeled "sediment".
- Now fold over the foil to wrap up the sediment pile. Press down on the pile as hard as you can. Gently unwrap it. The sedimentary crayon rock will be fragile but should hold together in a packed layer.
- Discuss the similarities between the sedimentary crayon rock and the real sedimentary rocks the students observed earlier.
- On the diagram, the arrow from "sediment" can be labeled "lithification - compacting and cementing sediments together". The next box can be labeled "sedimentary rock". Discuss this process as it occurs in the real world with layers being squeezed under other layers.
- Now get a helper to pass out the cups and go around yourself to fill each cup with hot water. Have another helper place containers of cooled water near each table or cluster of desks.
- Each student should use the foil to create a little boat for their sedimentary crayon rock and float his or her boat on the hot water. Watch as the heat from the water melts the crayon. Remove the foil when the wax is soft to the touch and the colors have swirled together but not so much that the colors are indistinguishable. Let the metamorphic crayon rock cool.
- Discuss the similarities between the metamorphic crayon rock and the real metamorphic rocks the students observed earlier.
- On the diagram, the arrow from "sedimentary rock" can be labeled "metamorphism - heat and pressure transforms the rock". The next box can be labeled "metamorphic rock". Discuss this process as it occurs in the real world with rocks being subjected to intense heat and pressure beneath the surface of the Earth.
- At this point, the temperature of the water in the cups may have cooled. Ask students to dump their water into the containers. Go around and refill each cup with hot water.
- Each student should put their metamorphic crayon rock back in the foil boat and float it on the hot water. This time, allow the wax to melt until a smooth pool of liquid wax forms and the colors blend together uniformly. Carefully remove the foil and let the igneous crayon rock cool.
- Discuss the similarities between the igneous crayon rock and the real igneous rocks the students observed earlier.
- On the diagram, the final arrow from "metamorphic rock" can be labeled "melting into magma then cooling". Discuss this process as it occurs in the real world with rocks being melted deep within the Earth then extruded again as volcanoes or bubbles of magma that do not reach the surface.
- Ask the students if they think this igneous rock could be turned into sedimentary rock? How? Could it be turned directly into metamorphic rock? How? Could a metamorphic rock be turned directly into sedimentary rock? How?
- Add additional arrows across the middle of the rock cycle to illustrate that any type of rock can turn into any other type of rock.
- If there is time, students can experiment with turning their igneous crayon rock into a new sedimentary, metamorphic, or igneous crayon rock.
- Clean up! Students can keep their crayon rocks.
This Earth Science lesson is taken from "MyScienceBox Lesson Plan" by Irene Salter (http://www.mysciencebox.org).
Permission for non-commercial use is given on condition of the license at (http://creativecommons.org/licenses/by-nc/2.5).
- You might have students complete the cut & paste vocabulary cards.
- Sing the "Rock Cycle Song" (sung to the tune of "Row, Row, Row Your Boat")
Has been formed in layers
Often found near water sources
With fossils from decayers
Then there's IGNEOUS rock
Here since Earth was born
Molten Lava, cooled and hardened
That's how it is formed
These two types of rocks
Can also be transformed
With pressure, heat and chemicals
METAMORPHIC they'll become.
Teaching Notes and Tips
Use caution when working with the hot water. I suggested using cereal bowls for the hot water instead of styrofoam cups. They would be more stable & less likely to tip & cause burns.
-Students' science notebooks should show the labeled rock cycle that was completed during the activity.
-When given a rock sample, students can describe the geologic process that formed it. Students may use notes taken during the activity and/or consult with group members. This may be helpful for students with learning difficulties.
MN Standard 5.III.A.5 Earth Structure & Processes
Students will explore the interaction of the lithosphere, atmosphere, biosphere, hydrosphere and space.
National Standards grades 5-8
Content Standard D: Structure of the earth system & Earth's history