Terrestrials or Aliens from Space: Comparing Igneous Rocks and Meteorites

-To work in collaborative groups to gather evidence by observing, recording and sketching.
-To research meteorites and igneous rocks for information regarding chemical composition.
-To use laboratory tools (balances, USB microscope, etc.) to gather further evidence.
-To draw conclusions based on observations, research and measurements about the origin of the "rocks."

The lesson is designed as an introductory lesson to the Earth and Space Science content of an 8th grade general science course. There are approximately 20 students divided into groups of four. With 40 minute periods, the entire lesson will probably take 3-4 days.

Students have previously (at earlier levels) learned something about the different types of rocks and minerals. In the 7th grade they worked with the periodic table of the elements. Part of this lesson is to review those ideas while leading into the current unit on the earth in space.

The use of measurement tools was reviewed at the beginning of the year, as was using the USB microscope (calibration and determining magnification). Density measurements were new to them at that time.

Background

This lesson is related to a lesson found in NASA's Exploring Meteorite Mysteries: Lesson 9: Meteorite Sleuths. I have not used the lessons in this module before, but parts of this lesson seemed helpful for what I am attempting here. I do not have access to the Meteorite Sample Disk NASA offers (although it would be possible to do the certification process here at nearby NASA Glenn Research Center-- for future reference). My lesson also requires students to be unaware of which samples are meteorites and which are igneous rocks, contrary to the original lesson. Since I am unlikely to be able to afford several samples of meteorites, I have decided to use unmarked pictures from the Internet for the first part of the activity. Ones marked with some sort of measurements would be best, which I haven't yet found.

Students should know something about igneous, sedimentary and metamorphic rocks and how they are formed, but I usually find they don't remember a lot. We will probably have to review the basic rock cycle, without getting into specific rocks in each category.

Students are also familiar with the Periodic Table of the Elements and did do research on some of the more common ones.

Students will have been introduced and done some work previously with density, which will be used at the end of the lesson.

The goal is to proceed from this lesson to a discussion of the formation of the solar system and the planets from what we discover about meteorites.

In-Class Activities

1. Class discussion: discuss the three categories of rocks and how they were formed. Review the rock cycle. Briefly discuss what they know about meteorites and establish what they are.

Question: Given samples of various igneous rocks and meteorites can it be determined which are which?
(Establish that for our purposes we will only be looking at the igneous rocks and discuss why. However, for a class that seems to remember more, it might be interesting to include some sedimentary rocks as well to separate out.)

2. In groups of four students will examine pictures of igneous rocks and meteorites:
a. Examine and make observations of pictures.
b. Record colors, shapes, textures, anything else distinctive.
c. Measure samples (if there is a scale)
d. Sketch the sample (to scale)
(There is a student worksheet for this in Lesson 9 of Exploring Meteorite Mysteries.)

3. After students have grouped their rocks they will discuss reasons why they believe they are igneous or meteorites and record their conclusions.

4.Research on the Internet: Each group will be given one igneous rock and one type of meteorite to research, including information about its mineral and chemical composition.

5. Jigsaw groups: One member of each group will meet with members of other groups to gather their information, then return to share with their own groups.

6. Measurement Lab: This part of the lesson will be done with actual samples of rocks, and some minerals, but without the meteorites. Perhaps some sort of small pieces of iron could be use to at least simulate the iron content of the meteorites.
a. Review density and how to find.
b. Mass samples using balances.
c. Find volume of samples using water displacement.
d. Compute densities of samples.
e. Re-group pictures from the first activity and provide evidence for their choices.

7. Class discussion: Have groups share their conclusions. Is it possible to tell which is which? Does the chemical composition of the minerals tell us anything about their densities and those of the rocks made up of them?

At Home Assignments

Research on the Internet would probable best be done at home, leaving more class time for small group discussions and drawing conclusions.

Materials

Introductory Activity
-Unmarked pictures from the Internet showing igneous rocks and meteorites
-Student worksheet (if desired) from Exploring Meteorite Mysteries or student lab books
-Colored pencils

Research
-Computers with Internet access
-Possible worksheet for recording essential information

Lab Activity
-Various sizes of graduated cyinders
-Water
-Digital balances
-Samples of igneous rocks and minerals found in the rocks and meteorites
-(Opt.) Small samples of iron
-USB microscope and computer

Standards

Strand I.A.1 Scientific Inquiry
Read, record, organize and interpret data in various forms produced by self and others in oral and written form.

Strand II.B.3 Earth and Space Science
Compare the composition of comets, asteroids and meteorites with that of earth.

The USB microscope is not necessary. There are pictures on the Internet of close-ups of the rocks and meteorites. The idea is mainly that scientists need to look more and more closely at the samples to determine its make-up.

There is also a "Meteorite Identification Start" activity on the Dawn Mission website from NASA (http://www.dawn-mission.org/Meteorite/experiment.asp)

Formative
Sketches and observations
Written conclusions from small groups
Internet research gathered
Notes from information gathered in jigsaw groups

Summative
-Conclusions from the entire lesson written out
-Possible Lesson 13: Solving a Mystery, from Exploring Meteorite Mysteries

Exploring Meteorite Mysteries (NASA EG-1997-08-104-HQ)
For images of igneous rocks and meteorites (so far):
http://www.geology.com
http://www.geology.about.com
http://www.dawn-mission.org/Meteorite/experiment.asp
http://www.windows.ucar.edu
For Meteorite Sample Disk requests:
JSC Educator Research Center
NASA Johnson Space Center
1601 NASA Road One
Houston, TX 77058-3696