This activity is appropriate after an introduction to the rock cycle. Students should already have been given a basic understanding of what causes the formation of sedimentary, igneous, and metamorphic rock.
Warm Up: (10 minutes)
As students enter the room, give each student a sample of sandstone and a sample of quartzite. As this is an individual activity, it is important that each student have his own sample. Have 2 small paper cups set up on the desk for each student.
Say, "Yesterday we learned about the rock cycle. Why is it considered a cycle?" Discuss the Rock Cycle briefly.
"Today you will have a chance to observe a transformed rock and the rock that it transformed from. You have each been given 2 samples of rock. Your task is to decide which of these samples is sedimentary rock and which is the metamorphic rock formed from that sedimentary rock (as we spoke of yesterday) by heat and pressure in the Earth."
"When you have decided which is the sedimentary and which is the metamorphic, place the sedimentary rock in the cup on the left and the metamorphic rock in the cup on the right."
"Compose a sentence or two about why you made the choice that you did."
Discussion: (5-10 minutes)
How did the two samples of rock feel and look differently? Talk about the sandy feel of the sandstone. What does this mean?
Ask the students to discuss why they made the choices they did.
After at least 5 minutes of discussion before revealing the correct answer, talk with the students about the formation of sedimentary and metamorphic rock. Review the rock cycle lesson, as necessary.
Ask: "What major player in the rock cycle is missing from this activity?" Igneous rock
Pass out a sample of igneous rock to each student. Have students work in groups of 2 to describe how each type of rock forms. As each group describes its type (sedimentary, metamorphic, or igneous rock) have the other students all find the appropriate sample and hold it up high.
Have students either complete a review from the text or define the related terms below:
sedimentary rock - type of rock formed by the pressing together of smaller particles of rock or the remains of living things
metamorphic rock - a type of rock formed when igneous or sedimentary rock changes under very high pressure
igneous rock - a type of rock formed from magma cooling