Core Curriculum/Oklahoma AIMS Education Foundation

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1 Topic Rocks Key Question How can models, drawings, and reading passages help you understand some ways that rocks form in layers? Learning Goals Students will: model how sediment layers can form rocks, read about sedimentary rocks, and identify some of the ways that sedimentary rocks form. Guiding Documents Project 2061 Benchmarks Rock is composed of different combinations of minerals. Smaller rocks come from the breakage and weathering of bedrock and larger rocks. Soil is made partly from weathered rock, partly from plant remains and also contains many living organisms. Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly, or that are too vast to be changed deliberately, or that are potentially dangerous. NRC Standard Some changes in the solid earth can be described as the rock cycle. Old rocks at the earth s surface weather, forming sediments that are buried, then compacted, heated, and often recrystallized into new rock. Eventually, those new rocks may be brought to the surface by the forces that drive plate motions, and the rock cycle continues. Science Earth science rocks and minerals Integrated Processes Observing Comparing and contrasting Relating Communicating Collecting and recording data Interpreting data Inferring Materials For each student group: a one-liter bottle with lid soil, sand, and pebbles (see Management 1) funnel (see Management 2) sedimentary rocks (see Management 5) hand lens water source Background Information Sedimentary rocks are made up of materials that were once a part of another rock. These parts were deposited as layers of loose materials. These parts are called sediments. Most sediment is deposited on ocean floors or at the bottom of rivers and lakes. Over time the loose sediments are formed into solid rocks. Sedimentary rocks are classified into three groups. They are grouped based on what the original sediments were. Clastic sedimentary rocks form from layers of sediments. Pressure causes the water around the sediments to be squeezed out and the sediments are cemented together. Sandstones, shales, and conglomerates form this way. Chemical sedimentary rocks form when rock fragments dissolve in water. Over time the water evaporates and the minerals that were in the rock crystallize into large deposits. Rock salt and gypsum form this way. Organic sedimentary rocks form from the sedimentary remains of shells, skeletons, and other plant and animals parts. Limestones and coals form this way. Management 1. You will need to gather builder s sand, potting soil, and small pebbles. These will be called Earth materials as well as sediments in this activity. Students will need to understand that these materials come from rocks that have been broken down as a result of weathering. The soil also contains organic materials. 2. You will need funnels that will permit the students to easily place the sand, soil, and pebbles into the bottles. Paper funnels sold to pour oil into cars are an inexpensive source for these. 3. Prepare one bottle with the three types of sediments and a second bottle with the three sediments and water. 4. Tell the students to fill the containers half-full with the three Earth materials and to pour in water so that the bottle is three-fourths full. 5. You will need samples of conglomerates, sandstones, limestones, and shales for each group. Core Curriculum/Oklahoma AIMS Education Foundation

2 Procedure 1. Ask the Key Question and state the Learning Goals. 2. Show the students the three Earth materials. Direct the students in a discussion about these Earth materials. Make sure the students understand that these materials are called sediments. 3. Point out to the students that these three materials came from other materials. The sand and pebbles are smaller pieces of rocks that have been broken down by processes on the Earth. The soil is a combination of sand and rocks as well as organic materials. Organic means that it was once living. Examples of organic materials found in the soil are decaying roots, leaves, as well as insects. 4. Direct the student s attention to the bottle that has just the Earth materials in it. Ask the students what Earth materials are in the container. (They may or may not be able to see the different type of materials.) 5. Show them the container with the Earth materials and the water. Ask them what they think the water in the bottle represents in this model. [It represents the moving water.] 6. Distribute a bottle with lid and hand lens to each group. Direct each student group to place the three Earth materials into their bottle and add water. 7. Tell the students to tighten the cap of the bottle and shake the bottle. Direct them to place the bottles in the center on the group and observe and record what they see happening in the bottle. Encourage them to use the hand lens when making observations. Distribute the sedimentary rock samples and have the students identify which layer they think the sample is most like. [The conglomerates are most like the bottom layer, the sandstone and limestone most like the middle layers, and the shale most like the top layer.] 8. Tell the students to gently turn the bottle upside down. Have them observe and record what they see happening in the bottle. 9. Distribute the reading passage on Learning about Layers. Have the students read and respond to the questions. Connecting Learning 1. In your own words, describe how sediments form layers. 2. What can happen to these layers over time? 3. Why is it useful in science to use models as well as drawings when you are learning about how rocks form? 4. What role does water play in the formation of rocks? 5. What are you wondering now? Core Curriculum/Oklahoma AIMS Education Foundation

3 Key Question How can models, drawings, and reading passages help you understand some ways that rocks form in layers? Learning Goals model how sediment layers can form rocks, read about sedimentary rocks, and identify some of the ways that sedimentary rocks form. Core Curriculum/Oklahoma AIMS Education Foundation

4 43 Modeling Sedimentary Rocks 1. Pour soil, sand, and pebbles into the bottle. 2. Add water and shake. 3. Observe the particles in the jar. 4. Sketch and describe the layers. Describe 5. Slowly turn the bottle upside down. 6. Sketch and describe. Sketch Describe Sketch In your journal, describe how this shows one way sedimentary rocks form. Core Curriculum/Oklahoma AIMS Education Foundation

5 Sedimentary rocks are made up of pieces of other rocks. These pieces are called sediments. Sediments get carried by wind, water, or ice and then are deposited in layers. Have you ever stirred sugar in water and watched it dissolve? If you let the water evaporate, a layer of sugar will be left in the bottom of the glass. Rock salt and gypsum form this way. sugar in layer of water sugar 1 6 The last kind of sedimentary rock forms from the remains of shells, skeletons, and other plant and animals parts. Over time the pressure of soil turns things into layers of rocks. Limestones and coals form this way. 7 Core Curriculum/Oklahoma AIMS Education Foundation

6 One kind of sedimentary rock is formed from layers of sediments. Pressure causes the water around the sediments to be squeezed out and the sediments are pushed together. Imagine placing a wet sponge between the palms of your hands and squeezing it. The water is squeezed out and the once plump layer of sponge becomes a thinner layer. Sandstones, shales, and conglomerates form this way. 3 4 Another kind of sedimentary rock forms when rock fragments dissolve in water. Over time the water evaporates and the minerals that were in the rock turn back into large layers of crystals. Most sediments are deposited on ocean floors. They can also be deposited at the bottom of rivers and lakes. Over time the loose sediments form into layers of solid rocks. 5 2 Core Curriculum/Oklahoma AIMS Education Foundation

7 Connecting Learning 1. In your own words, describe how sediments form layers. 2. What can happen to these layers over time? 3. Why is it useful in science to use models as well as drawings when you are learning about how rocks form? 4. What role does water play in the formation of rocks? 5. What are you wondering now? Core Curriculum/Oklahoma AIMS Education Foundation