Overview: Students observe and record the properties of selected rocks and minerals. Using reference resources, the students identify the specimens, distinguish between rocks and minerals, and classify the rocks as igneous, metamorphic, or sedimentary.
Booklink: Everybody Needs a Rock by Byrd Baylor, Aladdin Paperbacks, NY, 1974. ISBN 0-684-71051-8
Science Activity Link: Students work in groups of two or three to observe rocks and minerals, use reference resources to identify them, distinguish between rocks and minerals, and identify the three kinds of rocks.
Objective: Students will observe, identify, and classify rocks and minerals.
Science Processes and Content: Processes-Observing, communicating, classifying, predicting, inferring, and gathering and recording data. Content-Systems and subsystems, origins and composition of rocks and minerals, and Earth processes including vulcanism, mountain building, and erosion and sedimentation.
National Science Education Standards: Unifying Concepts and Processes, (1) Science as Inquiry, (2) Physical Science, (3) Life Science, (4) Earth and Space Science, (5) Science and Technology, (6) Science in Personal and Social Perspectives, (7) History and Nature of Science
Materials: Book Everybody Needs a Rock, multiple specimens of rocks and minerals (enough for students to work in groups of 2 or 3), (Note: rocks and minerals can be purchased from most science suppliers.), magnifying lenses,and references describing rocks and minerals
1. Read the book, Everybody Needs a Rock, discuss it with students, and tell them that they are going to go on a field trip to find a special rock...but first they must write their own rules for selecting a special rock. Have some student volunteers read their rules.
2. Now go on a rock collecting field trip. Each student should return with one special rock that closely fits his/her rules. Share and discuss their finds. Ask the students how they would change their rules if they were to go on another rock hunt. (See the QuickPlan "Rock Talk" for additional teaching ideas.)
3. In this next investigation, students will work in groups of 2 or 3 and will be given mystery rocks or minerals to observe and identify using written or computer identification references. The size of the student groups may be determined by the number of complete rock and mineral specimen sets you have available. More specimen sets and references equal more and smaller-sized student groups. Fewer specimen sets and references equal larger-sized student groups.
4. Teachers should have lots of possible specimens to choose from. The ones that worked well for me, because of their variations and distinctiveness, are: halite (mineral), pumice (igneous rock), talc (mineral), limestone (sedimentary rock), marble (metamorphic rock), galena (mineral), basalt (igneous rock), mica (mineral), granite (igneous rock), quartz (mineral), obsidian (igneous rock), and sandstone (sedimentary rock). The number of specimens can be reduced or increased to make the lesson easier or more challenging.
5. To get the students started and to establish a behavioral model for classroom procedure, one specimen can be selected for observation and identification. Halite is the one I selected but any other specimen could be used. All student groups have only halite. Ask them to observe it carefully, recording their observations. Then ask them to infer the identity and discuss their inferences. Now give them a single reference on halite and have them compare what they read to their observations, e.g. transparent, colorless, feels sticky, can stand up on any side, and dissolves easily in water. Use the reference to find out more about halite: all halite comes from the sea, it is a mineral, it is essential in the diets of animals including humans, and it is used as a seasoning, preservative, road de-icer, and raw material in the chemical industry. In this entire activity it is important to have the students observe carefully, accurately describe what they see, and use reference materials effectively.
6. Now give each student group a mystery set of rock and mineral specimens and access to references for identification. For instance, each group may have 10 mystery specimens to identify. First, they should observe all specimens carefully, recording and discussing their observations. Then they use references to identify the specimens, differentiate between rocks and minerals, and classify rock types. When all have finished, select groups to report their findings on and identification of one specimen. Follow with group discussions.
7. To conclude this activity, you may want to differentiate between rocks and minerals. For instance, each mineral contains the same kinds of particles. The particles of each mineral always form the same pattern. The crystals of each mineral always have the same definite shape. Rocks are made of minerals. However, in many rock types the minerals can't be recognized because the minerals are not in crystaline form. From the mystery rocks and minerals observed in class, identify the minerals, e.g. talc and mica and the rocks, e.g. basalt and sandstone. You may also want to distinguish among the three basic rock types; igneous, sedimentary, and metamorphic. Igneous rocks form when melted material inside the Earth or on the Earth's surface cools and becomes a solid, e.g. pumice. Sedimentary rocks are formed by deposits of particles carried in air or water. Thick layers form and become buried, e.g. limestone. Metamorphic rocks form when existing rocks are subjected to high temperatures and pressure for long periods of time, e.g. limestone is turned to marble.
8. Finally, as an additional challenge, you may provide each student with a mystery rock or mineral specimen as a home research assignment or have them research and use Moh's Scale of Hardness to test and report on their specimen.
Safety: Rocks and minerals should not be placed in the mouth or thrown.
Rocks and Minerals by Herbert S. Zim and Paul R. Shaffer, Golden Press, NY, 1957. ISBN 0-307-24499-7
The Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knapf, NY, 1978. ISBN 0-394-50269-8
A Field Guide to Rocks and Minerals by Frederick H. Pough, The Peterson Field Guide Series, Houghton Mifflin Company, Boston, 1960. ISBN 0-395-08106-8
The Pebble in My Pocket by Meredith Hooper and Chris Coady, Viking, NY, 1996. ISBN 0-670-86259-2
How Mountains Are Made by Kathleen Weidner Zoehfeld, Harper Collins Publishers, 1995. ISBN 0-06-445128-3