Rock Cycle
Lesson Plan by Carola Martin
Adapted from Rock Cycle Crayons by Veronica Addison
Overview: This lesson is a hands-on activity for students to explore and participate in the rock cycle. It
models the rock cycle using crayons, and allows the students to make observations, formulate hypotheses, and
evaluate their hypotheses.
Suggested grade level(s): Grades 38
Concepts covered:
earth science, geology, rock formation, cycles of the earth
3rd Grade: Observe and describe the unique physical characteristics of a variety
of rock types. Describe earth materials (rocks, minerals, water, soil, and fossils) by their physical
properties.State similarities and differences among earth materials.
8th Grade: Explain how igneous, metamorphic, and sedimentary rocks are related
in a rock cycle.
Standards:
Length of lesson:
Approximately 1 hour (time will be longer if you have fewer hot plates available)
I usually finish up the 2nd day with review of lab and eating the rock
Materials required:
rock samples (igneous, metamorphic, and sedimentary, and
specifically samples of basalt and pumice if available)
newspaper to cover tables
Hot plates (1 per group) or microwave
Small aluminum pie tin or muffin tins (1 per group + 2 additional) or paper bowls
Per student / group: 3 types of chocolate bars (broken into small chunks)
(same / similar color if possible)
grater
Ziploc bag (heavy duty)
Heavy book or block of wood
Lesson Format
Phase I.
Introduction
Have different samples of igneous, sedimentary, and metamorphic rocks without identification. Have the
students compare the rocks and make/discuss observations about the characteristics of each type.
Phase II.
Exploration & Concept Development
Step 1: Distribute the 3 different chocolate chunks to each student / group, introducing them as minerals or
igneous rock. Have the students make observations of their chocolate rock on their worksheet.
(ANSWER QUESTION 1)
Step 2: Hold the chocolate inside the Ziploc bag and use the grater to make shavings. (weathering) Continue
until all three different chocolates have been made into shavings. (Some students will take their time so you
may need to set a time limit on this step.) Zip the bags shut, removing as much air as possible. While the
Page 1 of 8
students are making the shavings, ask them what happens to rocks/minerals as they are exposed to the elements.
Discuss the three weathering agents (wind, water, ice).
Step 3: Ask the students what their chocolate has turned into now that it has been weathered. (Sediment) They
may need to look at the Rock Cycle Diagram on their worksheet. (ANSWER QUESTION 2) Moving the
sediments or shavings models the process of erosion. Depositing the sediments models the process of
deposition. Ask the students to hypothesize (ANSWER QUESTION 3) what will happen when pressure is
added to their pile of sediments. Have them write or draw the hypothesis on their worksheet.
Tip: You may want to take digital pictures of the “rocks” at each step to use for comparison at the end of the
activity.
Step 4: Each student should now place their bag flat on the table and compress the bag by applying pressure
with both hands. By applying pressure, this models the pressure that compacts and cements the sediments
buried inside the Earth. Ask the students what type of rock they have formed. (Sedimentary) How has it
changed? What caused the change? Compare the hypothesis to what actually occurred. (ANSWER
QUESTIONS 4 & 5)
Step 5: Have the students hypothesize (ANSWER QUESTION 6) what would happen if we added even
stronger pressure and some heat. Have the students rub their hands together quickly to feel the heat generated.
What would this compare to in the earth? (friction, tectonic plate movement)
Step 6: Have the students hold the bag in their hands and then rub their hands back and forth quickly. They
should feel a small amount of heat generated. Next have the students place the bag underneath a heavy book or
block of wood and press down on it as hard as they can. Observe the very tightly pressed shavings that represent
the metamorphic rocks that have been buried under greater pressure at greater depths inside the Earth. Ask the
students what type of rock they have formed. (Metamorphic) How has it changed? What caused the change?
Compare the hypothesis to what actually occurred. (ANSWER QUESTIONS 7&8)
Step 7: Ask the student to hypothesize (ANSWER QUESTION 9) what would happen if we heated the rock
using the microwave or hot plate. What would this compare to on earth? (Subduction, tectonic plate melting)
Step 8: Have each group remove their rocks (carefully) from the plastic bags and place into a paper bowl and
put it into the microwave or one pie pan and place it on the burner. (Careful: Chocolate can burn easily in the
microwave. Test this beforehand to get the correct heating time.) Heat it slowly while the students observe the
rocks melting. The heat from the microwave represents the tremendous heat from deep inside the Earth.
Step 9: After the chocolate has melted, allow the samples to cool at room temperature or put into a refrigerator.
(Depending on size they may need to cool and dry overnight.) The melted chocolate represents molten rock
material called magma or lava. What type of rock has been created? (Igneous) (ANSWER QUESTION 10)
How has it changed? What caused the change? Compare the hypothesis to what actually occurred. (ANSWER
QUESTION 11)
Step 10: Have the students look at the rock samples shown during the introduction. Can they identify which
rocks are igneous, sedimentary or metamorphic?
After being in the refrigerator, it is very easy to pop the chocolate out of the paper bowl. Just bend the bowl and
it comes out easily. You can put their igneous rock into plastic bags or eat it right then and there. I have the
students split up their own chocolate and divide evenly.
Page 2 of 8
+`9+
Phase III. Concept Development
The concepts in this lesson are pretty basic. The Rock Cycle is a group of changes. Igneous rock can change
into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into
igneous rock. Metamorphic rock can change into igneous or sedimentary rock. See Figure 1 below.
Igneous rock forms when magma cools and makes crystals. Magma is a hot liquid made of melted minerals.
The minerals can form crystals when they cool. Igneous rock can form underground, where the magma cools
slowly. Or, igneous rock can form above ground, where the magma cools quickly.
Figure 1: The different paths of the rock cycle
When it pours out on Earth's surface, magma is called lava, the same liquid rock matter that you see coming out
of volcanoes.
On Earth's surface, wind and water can break rock into pieces. They can also carry rock pieces to another place.
Usually, the rock pieces, called sediments, drop from the wind or water to make a layer. The layer can be buried
under other layers of sediments. After a long time the sediments can be cemented together to make sedimentary
rock. In this way, igneous rock can become sedimentary rock.
All rock can be heated. But where does the heat come from? Inside Earth there is heat from pressure (push your
hands together very hard and feel the heat). There is heat from friction (rub your hands together and feel the
heat). There is also heat from radioactive decay (the process that gives us nuclear power plants that make
electricity). Basically, the heat bakes the rock. Baked rock does not melt, but it does change. It forms crystals. If
it has crystals already, it forms larger crystals. Because this rock changes, it is called metamorphic. Remember
that a caterpillar changes to become a butterfly. That change is called metamorphosis. Metamorphosis can occur
in rock when they are heated to 300 to 700 degrees Celsius.
Page 3 of 8
When Earth's tectonic plates move around, they produce heat. When they collide, they build mountains and
metamorphose (met-ah-MORE-foes) the rock.
The rock cycle continues. Mountains made of metamorphic rocks can be broken up and washed away by
streams. New sediments from these mountains can make new sedimentary rock. The rock cycle never stops!
Phase IV. Extension
Ask the students to predict what will happen when the rock is cooled in different ways? How could we test this?
(water, ice, fan, etc). You may want to prepare pie tins containing water and ice to use for cooling two samples.
In nature, the cooling rate of magma affects the crystal formation of rocks. Pumice and Basalt are two common
rocks, which are chemically identical but have different appearances. Why? Have the students investigate.
Notes
 Review with a BrainPop Movie (www.brainpop.com)
 If you feel bold, you can try the “Rock Cycle Song” to the tune of “Row, Row, Row Your Boat”
Page 4 of 8
NAME: _________________________
THE ROCK CYCLE
1. Make observations of your igneous rock in the space below. (Color, size, shape, texture, etc)
2. What has your igneous rock turned into after it has been weathered?
3. In the space below, hypothesize what will happen if you added pressure to your bag of sediments. You
may also draw a picture to help explain.
4. What type of rock has your sediment become after you applied pressure?
5. How has the rock changed? What caused the change? Compare this to your hypothesis in #3 above.
6. In the space below, hypothesize what will happen if you added even more pressure and some heat. You
may also draw a picture to help explain.
Page 5 of 8
7. What type of rock has it become after you applied even more pressure?
8. How has the rock changed? What caused the change? Compare this to your hypothesis in #6 above.
9. In the space below, hypothesize what will happen if you heated the rock on a hot plate. What would this
compare to on earth?
10. What has your rock become after heated it using the hot plate?
11. How has the rock changed? What caused the change? Compare this to your hypothesis in #9 above.
Page 6 of 8
It may help to give each group a copy of this figure explaining the rock cycle if they have not yet been
introduced to the terminology.
Page 7 of 8
Rock Cycle Song
(Sing to the tune of "Row, Row, Row Your Boat")
SEDIMENTARY rock
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.
(Don't forget to sing this as a "Round"; after all, it is the Rock "Cycle"!)
The Rock Cycle Song is from the Charlestown Elementary School M.I.Smart! Website
Page 8 of 8