67. WHAT THE ROCKS TELL US

from Come Fly With Me – Exploring Science through aviation and aerospace concepts.

SUBJECT: Science
GRADE: 7,8,9
GROUP SIZE: Small
TIME: 2-45 minute periods
TYPE OF ACTIVITY: Student Investigation Teacher Demo
TEACHING STRATEGY: Expository Guided Discovery
CONCEPTS: Rock Identification Moon Rocks
SKILLS: Following Directions Collecting and Interpreting Data
Objectives: To have students use various methods to identify rocks; to relate the study of Earth rocks to Moon rocks.

rocks data sheet

Materials: Unknown rocks, numbered; dilute hydro-choloric acid; knife blade or nail; hand lens; colored pens or crayons, activity sheet; rock identification key; Moon Rocks (See end of activity for information).
Teacher Background Information:

Rocks, of course, cannot literally speak. But they do contain interesting stories and they can reveal their stories through the scientist’s experienced eyes and sophisticated instruments. The shape, size, arrangement and composition of the individual grains and crystals in a rock tell about the history of the rock. The rock’s internal “radioactive clock” tells us its age. Tiny tracks may even tell the radiation history of the Sun during the last 100,000 years.

In some aspects, the appearance of lunar rocks resembles that of Earth rocks. The minerals are the same. The grain sizes are comparable. The shapes are familiar. But in other aspects, their appearance differs significantly. For example, the Moon rock’s surface is pitted with tiny craters, and the rocks are extraordinarily fresh. In order to compare Moon rocks with Earth rocks, students will need some background in identifying various rocks. The activity sheet should help them to do that.
Procedure:

Provide activity sheets for each student or small group of 2 – 3. Provide a copy of a rock identification key to each student or group or have a couple at hand in a learning center where the activity can be completed.

Explain that the activity sheet is in three parts:

Part A can be completed by using the various identification methods the students should be familiar with (Acid, Streak, Hardness, Specific Gravity Tests).

Part B can be completed using their own observations and/or other sources such as their textbook or books on rocks.

Part C will require that they do some research, use their observations and experiences and think very carefully about what they have read and observed. Finally, provide the students with the set of Moon Rocks obtained from NASA and complete some of the activities provided.

To obtain Moon Rocks requires that a teacher be certified by NASA at a workshop where trained personnel provide insight into how to use the Moon Rocks most effectively in the classroom. Security information is also provided at that time. Contact the NASA Teacher Resource Center for your area.
ACTIVITY SHEET

PART A

  1. Divide a sheet of paper into five columns
  2. At the head of the first column write UNKNOWN SAMPLE. Title the remaining columns as follows: ROCK NAME, ROCK FAMILY, DRAWING, OBSERVATIONS.
  3. Write the number of each of the rock samples down the left side of the page, as shown.
  4. Use the key your teacher provides to identify the unknown rocks. Indicate whether the sample belongs to the igneous, sedimentary or metamorphic family. Allow enough space to draw and color each rock in the fourth column.
  5. Record anything unusual you observe in the OBSERVATIONS column.

PART B

Sometimes it is very difficult to tell whether a rock is igneous, sedimentary or metamorphic. Make a table, such as the one shown, and list as many of the outstanding features you can think of for each family of rocks. You may use your own observations or check with other sources such as books on rocks or a science textbook that covers this area.
PART C

Answer the following questions:

  1. What might be one reason two samples of the same rock type sometimes look different?
  2. Why do you suppose most of the rocks we see at the surface of the Earth are in the sedimentary family?
  3. What may have caused the bands of color to form in gneiss? In what kind of rock are layers usually found? How is gneiss different from that kind of rock?

ROCK IDENTIFICATION KEY

Name of rock Description
1. Basalt dark gray to black; crystals not usually visible; heavier than #10
2. Bituminous soft, shiny coal; cannot be scratched by fingernail
3. Conglomerate cemented pebbles
4. Gabbro large, dark, interlocking crystals
5. Gneiss bands of color that may or may not be bent; often visible crystals
6. Granite interlocking pink, gray, and dark crystals
7. Limestone may contain tiny shells or interlocking crystals; usually light-colored; fizzes in acid
8. Marble color varies, may appear very crystalline; fizzes in acid
9. Obsidian dark; glassy-looking; fractures with curved surface
10. Pumice lightweight and holey; looks like a cinder; comes from volcanoes
11. Rhyolite pinkish-tan; crystals not visible without magnification
12. Sandstone cemented sand grains; color may vary
13. Schist may have long stretched crystals; may shimmer or look flaky
14. Shale color varies but usually dark; smells musty when it is moistened
15. Slate looks like a piece of blackboard; harder than #14

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.