Let's Take a Rock Apart!

An activity adapted from Investigating the Earth from the Earth Science Curriculum Project (ESCP)

Type of Lesson: Hands-on activity and discussion

Time Needed: 20 minutes

National Standards Addressed

Earth and Space Science, Grades K-4: Earth materials are solid rocks and soils, water, and the gases of the atmosphere. The varied materials have different physical and chemical properties, which make them useful in different ways, for example, as building materials, as sources of fuel, or for growing the plants we use as food. Earth materials provide many of the resources that humans use.

Earth and Space Science, Grades 5-8: Some changes in the solid earth can be described as the “rock cycle.” Old rocks at the earth’s surface weather, forming sediments that are buried, then compacted, heated, and often recrystallized into new rock. Eventually, those new rocks may be brought to the surface by the forces that drive plate motions, and the rock cycle continues.

Physical Science, Grades 5-8: A substance has characteristic properties, such as density, a boiling point, and solubility, all of which are independent of the amount of the sample. A mixture of substances often can be separated into the original substances using one or more of the characteristic properties.

Earth and Space Science, Grades 9-12: Interactions among the solid earth, the oceans, the atmosphere and organisms have resulted in the ongoing evolution of the earth system. We can observe some changes such as earthquakes and volcanic eruptions on a human time scale, but many processes such as mountain building and plate movements take place over hundreds of millions of years.

Quick Summary of Lesson

The student will take a crushed rock and sort the minerals by color and other properties. They will learn what minerals make up a crushed rock (in this case, granite).


Mineral specimens - milky quartz, feldspar, mica
Crushed granite rock - use granite or granite pegmatite (You do not need a huge amount of crushed granite. One film canister will be enough for a class of 45 students.)
each student will need 1 hand lens
each student will need 2 toothpicks
each student will need student worksheet available in Student Activity Sheet section below


1. Using the hand lens and two toothpicks, students are to sort the crushed rock. They should sort the material into the following categories (as seen on Student Worksheet):
a. all white
b. all pink
c. shiny blacks and grays
d. dull black
e. all other pieces
2. Now, the piles should contain similar looking material. Students have sorted by the characteristic of color. Now, have students use the hands lens to observe and describe each mineral pile. Students should record the color, luster, and cleavage of the pieces in the White, Pink and Shiny Black/Gray piles. Students can write these characteristics next to the circles of their Venn diagrams.
3. Give each student one mineral sample (either milky quartz, feldspar or mica). Tell the students to place this larger mineral sample in the correct circle of the Venn diagram.
4. Have students answer discussion questions on their individual worksheets.
5. Use discussion questions to lead class discussion.

Student Activity Sheet

Please click here for student activity sheets. All activities on the Windows to the Universe site may be printed and reproduced if being used for educational purposes.

Notes to the Teacher

First, please see the Teacher Key for this exercise.

Rocks and minerals have certain properties by which they may be described and identified. For rocks, these properties depend on the types of minerals from which they were made. In this activity, students observe, sort and classify the minerals that make up a crushed granite rock. The sorting is done according to physical properties which include color, luster and cleavage (hardness may also be tested and recorded as shown on the Teacher Key).

Film canisters full of crushed granite can be ordered from Dave Mastie (teacher). Please contact him at mastie@umich.edu to inquire about price and shipping.
Be sure to shake the container containing the crushed granite well so that each student gets a representative sampling of the material. Don't place too much crushed material on the Venn diagram at the crossmarked spot. Just cover the space with crushed particles. Remember, you have enough crushed material in one film canister for a class of 45 students. The sorting should take 10-15 minutes. At the end of this activity, make sure you collect all materials. Everything can be used again.

There are several easy connections to make with this lesson. The words granite, attribute, feldspar, property, quartz and mica could be used in a spelling lesson. Your class could discuss the uses of granite in buildings and monuments and tombstones during social studies class. Easy math connections include having students figure out percents of each mineral class within the granite rock. Compare those to percents that other students found and come up with class average. Finally, you could use this tidbit to lead a math exercise. Granite is the bedrock under New York City. It can hold 20,000 pounds per square inch. How much can a city block hold?

Recommended assessment includes using the large, unlabeled teacher specimens on the next day of class to drill, reinforce or quiz the previous day's lesson.

Need More Information? Try Using Windows to the Universe

Please use these links for further ideas or more information:
An introduction to Minerals
Main Geology Section
Types of Rocks

Last modified March 15, 2002 by the Windows Team

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