Name
Period
Date
CHAPTER 3 CHAPTER INVESTIGATION B
Rock Classification
MATERIALS



magnifying lens
6-8 rock samples
Rock Classification Key
OVERVIEW AND PURPOSE
In this activity, you will examine rock samples and refer to a rock classification key. You
will classify each sample as igneous, sedimentary, or metamorphic.
PROCEDURE
1. Get a numbered rock sample. Record its number in the data table on the next
page.
Table 1
Sample Number
Description of Its Visible
Properties
Rock Class
2. Observe the sample as a whole. Then closely examine it with the hand lens. Record in
your table all visual properties of the sample. For example, include properties such as
mineral or sediment size, layering, or banding.
3. Look at the classification key. Each item in the key consists of paired statements. Start
with item 1 of the key. Choose the statement that best describes the rock you are
examining. Look at the end of the statement and then go to the item number indicated.
4. Examine the rock sample again and choose the statement that best describes the rock.
5. Continue to work through the key until your choices lead you to a classification that
fits your rock. Repeat steps 1-4 for each of the numbered samples.
OBSERVE AND ANALYZE
1. Interpret Referring to the Rock Classification Key and the observations you recorded,
write the type of each rock in your data table.
2. Identify Limits What problems, if any, did you experience in applying the key?
Which samples did not seem to fit easily into a category? How could you improve the
key?
CONCLUDE
1. Compare and Contrast How are igneous and metamorphic rocks similar? How can
you tell them apart?
2. Analyze Examine a sedimentary rock sample in which visible particles are cemented
together. In addition to sight, what other sense could help you classify the rock sample?
Explain your answer.
3. Apply What have you learned from this investigation that would help you make a
classification key that someone else could follow? How would you make a key to classify
a music collection? Write two pairs of numbered statements that would start the
classification process.
Rock Classification Key
ANSWER KEY
Observe and Analyze
1. 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.
They are different in that the minerals in metamorphic rocks tend to be lined up in bands
or layers.
2. Touch could help identify a sedimentary rock made of relatively large particles.
3. Answers will vary. Sample answer: 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



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


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.