Name
Period
Date
CHAPTER 3 CHAPTER INVESTIGATION A
Rock Classification
MATERIALS
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hand lens
6-8 rock samples
Rock Classification Key data sheet
PURPOSE
In this activity, you will:
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look at rock samples and a key that will help you classify them
classify the rock samples. The rocks are igneous, sedimentary, or metamorphic.
PROCEDURE
Check off each step as you do it
1. Use the data table below to record your data.
Data Table 3.1
Sample Number
Description of Visible Properties
2. Choose a rock sample.
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Get a numbered rock sample.
Record its number in the data table.
Rock Type
3. Look carefully at the rock sample.
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Look at the sample with your eyes alone.
Examine the sample with the hand lens.
Write what you observed in the data table under "Description of Visible Properties."
4. Classify the rock sample.
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Look at the Rock Classification Key. Each step of the key has two statements.
Start with Step 1 of the key. Choose the statement that best describes your rock sample.
Look at the end of the statement. Go to the step number it shows.
5. Classify the rock sample.
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Look at the next pair of statements. Examine the rock sample.
Choose the statement that best describes your sample.
Go to the next step number it shows.
Work through the key. Your choices should lead you to a classification that fits your rock.
6. Repeat Steps 2-5 for each rock sample.
OBSERVE AND ANALYZE
1. Interpret Use the Rock Classification Key and the information in the table to find the rock type. Write the type
of each rock in the "Rock Type" column.
2. Identify Limits Did you have problems using the key? If so, what were they?
Which samples did not fit easily into a category?
How could you improve the key?
CONCLUDE
1. Compare and Contrast How are igneous and metamorphic rocks alike?
How can you tell igneous and metamorphic rocks apart?
2. Analyze Examine a sedimentary rock sample in which you can see particles that are held together. In addition
to sight, what other sense could help you classify the rock?
3. Apply Think about what you learned from this lab that would help you make a classification key that someone
else could use. How would you make a key to classify a collection of music CDs?
Write the first pair of statements that would start your music CD classification key. Use the Rock Classification
Key as a model.
Rock Classification Key
ANSWER KEY
Observe and Analyze
1. Students must correctly classify the rock samples as igneous, sedimentary, or metamorphic using the
classification key.
Sample data: 1, mineral crystals and speckled, igneous; 2, sea fossils, sedimentary; 3, wavy bands and shiny,
metamorphic
2. Students could have experienced some difficulty in matching the characteristics of their samples exactly to the
descriptions in the key. Samples that did not fit easily into a category will vary depending on the samples used.
Accept all reasonable suggestions for improving the key.
Conclude
1. Igneous and metamorphic rocks are similar in that they are both made of mineral crystals that fit tightly
together and may be large enough to see without magnification.
The minerals in metamorphic rocks tend to be lined up in bands or layers, or metamorphic rocks tend to be shiny.
2. Touch could help identify a sedimentary rock made of relatively large particles.
3. Answers will vary from student to student.
A key for a music collection might start with questions such as what type of music it is, when it was recorded, or
who the recording artist is.
TEACHER NOTES
Lab Preparation
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Copy and distribute the Rock Classification Key to each group of students. Review how to use it.
You might increase the number of rock samples to ten, if possible. Do not use slate (too similar to shale)
or limestone (can be difficult to identify without testing with hydrochloric acid).
Prior to the investigation, have students read through the investigation and prepare their data tables. Or
you may wish to copy and distribute datasheets and rubrics.
UNIT RESOURCE BOOK, pp. 196-205
SCIENCE TOOLKIT, F15
Lab Management
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Remind students that visual properties include size of particles or mineral
If students do not understand how to use the classification key, demonstrate the process with one rock
sample.
INCLUSION Encourage students with vision impairments to handle the rock samples to feel their textures.