Teacher Sheet Categorize Samples of Rocks as Sedimentary, Metamorphic, or Igneous

Time Required: 45-minute class period Student Background: Students should have finished and reviewed rock categories and testing procedures. Materials Needed: 10 different rock samples representing all three categories writing instrument Advance Preparation: Gather and organize rock samples so that each student has a different set of rocks. Place 10 samples into each tray and number each rock (vary the number of rocks within each category so students have different samples; this reduces the chance of copying). Label trays and create a key for each tray. Make copies of Be a Rock Hound (three pages) for each student. Procedures:

1. Hand out Be a Rock Hound and student response sheet and briefly explain the procedure.

2. Tell students they are working as individuals. 3. Have students get the samples.

4. Have students separate their samples into three groups: sedimentary, igneous, and metamorphic. 5. Have students list which characteristics they found for each rock and list them by rock number.

Scoring Guide: Correct category -- 1 point each (total 10 points) Correct rock characteristics -- 1 point each (total 10 points) Total: 20 points

Student Sheet Categorize Samples of Rocks as Sedimentary, Metamorphic, or Igneous

Problem: You have been given 10 samples of rocks.

1. Look at the handout Characteristics of Sedimentary Rocks. Pick out the sedimentary rocks from the samples and set them aside; label them as sedimentary rocks. 2. Look at the handout Characteristics of Igneous Rocks. Pick out the igneous rocks from your samples and label them as igneous rocks. 3. Look at the handout Characteristics of Metamorphic Rocks. Check the remaining specimens to see if they have the characteristics listed on the handout. Label them as metamorphic rocks. 4. If you have samples left over decide to which group you think they belong. Have your instructor check your work.

Safety: Do not drop rocks. Do not put rocks in mouth.

Student Response Sheet Name:_____________________________ Tray Number:_____________

Sample Number

Category (S, M, I)

Identification Traits

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Be a Rock Hound Rock collecting is an interesting and challenging hobby. There are hundreds of different kinds of rocks. To be a successful rock collector, you must be able to identify and classify rock samples. So you must know the classification system of rocks. This system is based on examination of a rocks physical properties. These properties will identify the rock as igneous, sedimentary, or metamorphic. Physical and chemical tests will further identify the rock as a particular kind of igneous, sedimentary, or metamorphic rock. To find out firsthand what rock collecting involves, you will identify nine unknown rock samples provided by your teacher. Select one numbered rock sample. Examine it carefully. What are its most obvious physical properties? Compare these properties to the characteristics of each type of rock listed in the table on this page. Select the rock type whose characteristics best match the properties of the sample. Repeat this procedure for each sample provided. By the time you finish, you should have three samples of each type of rock.

Characteristics of Igneous Rocks 1. Igneous rocks may contain crystals, which often can be seen with the unaided eye. (See figure 1). 2. Igneous rocks that cooled quickly contain no crystals and appear glassy. (See figure 2). 3. Igneous rocks may be found in many colors. They often show different-colored crystals that are not in bands. 4. Igneous rocks often have bubble holes where gases were trapped when the rock cooled.

Characteristics of Sedimentary Rocks 1. Most sedimentary rocks are made of fragments of other rocks. These fragments look very much like sediment. Some sedimentary rocks have a range of particle sizes. Other sedimentary rocks consist of one sediment size. (See figure 1) 2. Some sedimentary rocks are composed of plant and animal products or remains. Such rocks often contain fossils. (See figure 2) 3. Sedimentary rocks often have distinct parallel layers. (See figure 3) 4. Sedimentary rocks often appear dull.

Characteristics of Metamorphic Rocks

1. Metamorphic rocks often look like igneous rocks except that they show bands of color. (See figure 1) 2. Metamorphic rocks may show signs of bending. (See figure 2) 3. Mineral crystals in metamorphic rocks are generally flattened. 4. Metamorphic rocks often have a sheen (shiny look) to them. 5. Metamorphic rocks are generally more compact than other types of rocks, which makes them harder. Sometimes they will have a ringing sound to them if you tap on them.