Science Concept: Sedimentary rocks are made from layers of sediments and rocks. Teacher s NOTE: Allowing students to explore the variety of sedimentary rocks before this lesson may increase student understanding. This will results in students possessing a wider vocabulary and familiarity with sedimentary rocks, and increase their understanding when discussing layers of sediment. Objectives: The student will: describe how sedimentary rocks are made from deposits of sediments and smaller rocks; communicate how layers contain distinct rock sediments with unique textures, color, patterns, and shapes; and create a recipe using similes to compare layers in a sandwich to sedimentary rock layers. GLEs Addressed: Science [6] SD1.1 The student demonstrates an understanding of geochemical cycles by exploring the rock cycle and its relationship to igneous, metamorphic, and sedimentary rocks. [6] SA1.1 The student demonstrates an understanding of the processes of science by asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating. Writing [6] W2.2.3 The student writes for a variety of purposes and audiences by using expressive language when responding to literature or producing text (e.g., writer s notebook, memoirs, poetry, plays, or lyrics). Vocabulary: deposition - the accumulation of material dropped because of a slackening movement of the transporting medium, e.g., water or wind deposits - any accumulation of sediment erosion - removal of material by water, wind, or ice. As soon as a rock particle (loosened by weathering) moves, by some flowing agent such as air, water or ice, it is erosion force - strength or power exerted upon an object; in physics, an influence on a body or system, producing or tending to produce a change in movement or in shape or other effects; the intensity of such an influence layering - to form or arrange in layers sedimentary rock - sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on Earth s surface. Sedimentary rocks often have distinctive layering or bedding weathering - (1) the physical disintegration or chemical decomposition of rock due to wind, rain, heat, freezing, thawing, etc. (2) The response of materials that were once in equilibrium within the earth s crust to new conditions at or near contact with water, air, or living matter. The breakdown of rock through a combination of chemical, physical, geological, and biological processes. The ultimate outcome is the generation of soil Science Teacher Education Program 2009 Geophysical Institute, UAF 377 SEDIMENTARY SANDWICH
Materials: Bread (two slices per student, minimum) Chopsticks, or other similar object (one per student) Clay Colored sand Condiments (e.g., mayonnaise) Gravel, small sized Half-pint canning, or similar sized, jars with lids Plastic knives Rice and other materials to add to sedimentary rock strata Rocks, of various shapes and sizes, small enough to fit inside baby food jars (10 per student) Sand Sandwich meat (e.g., ham, turkey, tuna, etc.) Science journal Silt Toppings for sandwiches (e.g., sprouts, tomato, pickles, lettuce, cheese) TEACHER INFORMATION SHEET: Background Information Activity Procedure: Please refer to the assessment task and scoring rubric located at the end of these instructions. Discuss the assessment descriptors with the class before teaching this lesson. Gear Up Process Skills: observing, inferring, and communicating 1. Divide students into pairs. Distribute rocks to each pair. Ask students to stack the rocks into pyramidshaped cones called Cairns (see TEACHER INFORMATION SHEET). Student pairs may use all shapes and sizes of rocks provided. After 5-8 minutes of building, gather as a class, and ask students to share their Cairns. 2. Ask students how they built their cairn. What was difficult in the process? What could you use to keep the rocks from falling apart? 3. Write student responses on the board. Ask students to write one paragraph summarizing the activity (including answers to the questions posed) in their science journal. Circulate around the room and document which students understand the process of stacking and layering. (NOTE: This information may be used to group students according to their understanding during Explore.) 4. Share the information in the TEACHER INFORMATION SHEET with students. Explain cairns are constructed by humans, but nature makes its own stacked rocks called sedimentary rocks made from sediments layering over millions of years, and eventually solidifying into a solid, layered rock by enduring tremendous pressure. Explore Process Skills: investigating, predicting, and developing models Teacher s NOTE: Students may work together or alone on this project, but partners are encouraged. 5. Explain students will build a model of sedimentary rock strata using a jar and various soils, small rocks, sand, silt, colored sand, clay, etc. 6. Distribute jars and materials. Ask students to add small amounts of the materials to the jar in thin layers, one on top of the last. Provide chopsticks for students to move the layers around or distort the layers if they choose. 7. Instruct students to cap the jars when finished. Allow 10 12 minutes for this process students that Science Teacher Education Program 2009 Geophysical Institute, UAF 378 SEDIMENTARY SANDWICH
finish early may look at other students models. Circulate between groups and check for understanding. Prompt thinking by asking questions: a. How did the layers interact? b. Did the top layers filter down? c. Why did you choose that particular layer order? d. Did you see another group with the same layer pattern? e. Assuming the sediments in your jar were under extreme pressure for thousands (millions) of years, what might happen to the loose sediments? 8. Ask students to list the layers of sediment from the bottom to top, one layer at a time, in their science journals, and write down any questions they might have about sedimentary rocks. Generalize Process Skills: inferring, describing, and making generalizations 9. Ask students to look at the layers of sediment. Discuss the following questions: a. Do any of the materials mix as they are laid down? b. What shapes or textures do you see in the layers? c. Have you seen sedimentary layers before in a different context? d. Where might you find sedimentary layers (material laying atop of materials)? e. How long do you think the rock/soil process might take in real life? f. Where would this process occur faster? Slower? g. What forces might cause the weathering process that leads to sedimentation of rocks and soils? Apply Process Skill: inferring, describing, and making generalizations 10. Explain students will build their own sandwich using layering techniques and choosing from a variety of ingredients. Unique sandwiches are encouraged. Students will need to push the layers together and observe the pressure exerted on the layers. 11. Distribute materials (bread, meat, toppings, condiments, knives) and allow students to build their sandwiches. Encourage students to say aloud what they are doing as they build their sandwiches. (e.g., I am laying one layer on top of another. I am applying pressure to the layers to glue them together.) When finished, instruct students to cut their sandwich in half creating a clean cross-section. 12. Ask students to respond to the following questions in their journals: What does this cross-section remind you of? Why? Science Teacher Education Program 2009 Geophysical Institute, UAF 379 SEDIMENTARY SANDWICH
Assessment Task: 1. Write a recipe for a sandwich that includes similes for each ingredient (layer) comparing the actual ingredient with a rock sediment layer. (e.g., Tomatoes are like red coral that fell to the ocean floor. Over time it was covered by sand. Lettuce is like a layer of silt deposited on a riverbank.) 2. Draw a cross-section diagram of the sandwich that includes at least four labels that identify texture, pattern, color, and shape. Include at least one caption that describes how different ingredients layer one on top of the next. Make a connection to sedimentary rocks by explaining how sedimentary rocks are formed through layering and deposition of smaller rocks and sediments. Rubric: Objective GLE Below Proficient Proficient Above Proficient The student describes how sedimentary rocks are made from deposits of smaller rocks and sediments. The student communicates how layers contain distinct rock sediments with unique textures, color, patterns, and shapes. The student will create a recipe using similes to compare layers in a sandwich to sedimentary rock layers. [6] SD1.1 The student may describe how sedimentary rocks layer, or how layers are made from deposits of smaller rocks and sediments. [6] SA1.1 The student may create a diagram of a sandwich that includes less than four labels for textures, color, pattern, and shape. [6] W2.2.3 The student writes a recipe with less than five or fails to compare two unlike things using similes (like or as). The student describes how in sedimentary rocks the layers stack one on top of the next, and how the layers are made from deposits of smaller rocks and sediments. The student creates a crosssection diagram of sandwich layers and includes four labels that identify texture, color, pattern, and shape, and includes a caption describing how ingredients layer one on top of the next. The student writes a recipe with five similes and compares each the sandwich ingredients to deposit layers in sedimentary rock. The student describes how in sedimentary rock the layers stack one on top of the next, how the layers are made from deposits of smaller rocks and sediments, and how pressure solidifies the rock. The student creates a crosssection diagram of sandwich layers and includes five or more labels that identify texture, color, pattern, and shape, and includes two or more captions describing how ingredients layer one on top of the next. The student writes a recipe with five similes, compares each the sandwich ingredients to deposit layers in sedimentary rock, and includes a metaphor. Science Teacher Education Program 2009 Geophysical Institute, UAF 380 SEDIMENTARY SANDWICH
TEACHER INFORMATION SHEET: background information Cairn A cairn is an artificial stack of rocks found most commonly along waterways, mountains, and paths. They are built to mark trails, burial sites, or identify religious sites or historic locations. The Inuit (indigenous people of the artic) construct human-shaped cairns (inuksuits) as directional markers in the Canadian Arctic. Cairns are found all over the world, even underwater! Sedimentary Rocks Sedimentary rock is formed when sediments are deposited by wind, gravity, ice, air, or water and built into layers over time. The layers (often made up of many types of sediment) are buried and solidify together (lithification the formation of rocks) to form layered beds (strata). Sedimentary rock can contain fossils, as well as clues to the original rock fragments. The process of squeezing the layers of sediments together (extreme pressure and cementation) does not destroy the fossils, but the process takes a very, very long time (millions of years). Sedimentary rocks cover the majority of Earth. They can be classified into three groups: clastic, fine grains weathered and deposited (e.g., shale and sandstone); organic, materials made from organisms (e.g., limestone and oil shale); and chemical, formed when mineral solutions evaporate (e.g., halite and gypsum). Common sedimentary rocks: Limestone: made up of particles of the same size (can contain fossils) Clay: very small sediments Sandstone: sharp corners medium sized particles Loess: formed by sediment polished by wind Conglomerate: rounded pebbles of different sizes, tumbled by water and cemented together Breccia: sharp cornered rocks of different sizes, not smoothed by water but cemented together Tillite: made of particles moved and deposited by glaciers all sizes and textures Science Teacher Education Program 2009 Geophysical Institute, UAF 381 SEDIMENTARY SANDWICH
TEACHER INFORMATION SHEET: background information The Rock Cycle Heat/Pressure Sedimentary Erosion/ Deposition Erosion/ Deposition Melting Metamorphic Igneous Melting Fun Facts The White House in Washington, DC is made of sandstone. Oil (petroleum) deposits can be found in the porous reservoirs of sedimentary rocks. Quartz (a sediment in sedimentary rocks) is the most common mineral on earth. Breccia is a rock composed of large, sharp fragments cemented together. Limestone is made from shells and sea creatures that collect at the bottom of the ocean. Sandstone is most often formed in oceans. Limestone fizzes in vinegar. Gypsum often looks like a flower. Sandstone feels like sandpaper. Science Teacher Education Program 2009 Geophysical Institute, UAF 382 SEDIMENTARY SANDWICH