Science Teacher Education Program ©2009 Geophysical Institute, UAF 377 SEDIMENTARY SANDWICH

SEDIMENTARY SANDWICH

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 winddeposits - any accumulation of sedimenterosion - 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 erosionforce - 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 layerssedimentary 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 378 SEDIMENTARY SANDWICH

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 UpProcess Skills: observing, inferring, and communicating

1. Divide students into pairs. Distribute rocks to each pair. Ask students to stack the rocks into pyramid-shaped 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.

ExploreProcess 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 379 SEDIMENTARY SANDWICH

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.

GeneralizeProcess 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?

ApplyProcess 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 380 SEDIMENTARY SANDWICH

SED

IMEN

TARY

SA

ND

WIC

H

Ass

essm

ent T

ask:

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for e

ach

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ayer

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ith a

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e.g.

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that

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east

four

labe

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Rubr

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Pro

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The

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[6] S

D1.

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The

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in

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rock

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on to

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next

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d ho

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and

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how

in

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[6] W

2.2.

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hor.

Science Teacher Education Program ©2009 Geophysical Institute, UAF 381 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 sedimentsSandstone: sharp corners – medium sized particlesLoess: formed by sediment polished by wind Conglomerate: rounded pebbles of different sizes, tumbled by water and cemented togetherBreccia: sharp cornered rocks of different sizes, not smoothed by water but cemented togetherTillite: made of particles moved and deposited by glaciers – all sizes and textures

Science Teacher Education Program ©2009 Geophysical Institute, UAF 382 SEDIMENTARY SANDWICH

TEACHER INFORMATION SHEET: “bACkGROUND INFORMATION”

The Rock Cycle

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.

Sedimentary

Igneous Metamorphic

Heat/Pressure

Melting

Melting

Erosion/ Deposition

Erosion/ Deposition