Lesson 42: Sedimentary Rocks 2 Days
State Standard5.1 Scientific investigation and reasoning. The student conducts classroom and outdoor investigations following home and school safety procedures and environmentally appropriate and ethical practices. The student is expected to:
(A) demonstrate safe practices and the use of safety equipment as described in the
Texas Safety Standards during classroom and outdoor investigations;
5.2 Scientific investigation and reasoning. The student uses scientific methods during laboratory and outdoor investigations. The student is expected to:
(A) describe, plan, and implement simple experimental investigations testing one
variable;
(B) ask well-defined questions, formulate testable hypotheses, and select and use
appropriate equipment and technology;
(C) collect information by detailed observations and accurate measuring;
(D) analyze and interpret information to construct reasonable explanations from
direct (observable) and indirect (inferred) evidence;
(E) demonstrate that repeated investigations may increase the reliability of results;
(F) communicate valid conclusions in both written and verbal forms;
5.3 Scientific investigation and reasoning. The student uses critical thinking and scientific problem solving to make informed decisions. The student is expected to:
(C) draw or develop a model that represents how something works or looks that
cannot be seen such as how a soda dispensing machine works; and
(D) connect grade-level appropriate science concepts with the history of science,
science careers, and contributions of scientists.
5.7 Earth and Space. The student knows Earth's surface is constantly changing and consists of useful resources. The student is expected to:
(A) explore the processes that led to the formation of sedimentary rocks and fossil fuels; R
R = Readiness Standard
Statement of Learning Objective
The students will explore the process that led to the formation of sedimentary rocks.
Essential Question:
How has Earth’s surface changed over time?
Vocabulary: sedimentary rock, sediment, natural resource, cementation, compaction
Materials
Engage: Snickers candy bar, picture of cliff (La Jolla, California)
Explore: Ziploc baggie (one per group), sand, small rocks, small pieces of plants, small
pieces of wood (you will need to provide these if you don’t have the students find
them on the school grounds), Dixie cups (bathroom size - 2 per group), liquid
glue, craft sticks
Explain: Day 1 - 6 sedimentators (or one for each table) Earth Science National
Geographic books, science notebooks; Day 2 – 1L plastic bottle with top cut off
(or jar), rocks, sand, pebbles, small shells, soil, mulch, study guides, science
notebooks, chart paper and markers (for teacher to create anchor chart),
sedimentary rock formation Power Point slide, hand lenses
Elaborate: layer cake (homemade or store bought – the more layers the better), clear
straws, colored pencils, science notebook, Cool Careers in Earth Sciences book
(one of the books in the Sally Ride book set)
Evaluate: diagram of rock layers, index cards (or small pieces of paper)
Common Learner Misconceptions
Misconception / Correction Statement
· The Earth’s surface is unchanging.
· Sedimentary rock layers were all made at the same time.
· The oldest rocks are ones with dinosaur fossils.
· The only way to see what is under the surface of Earth is to dig a big hole. / · The Earth’s surface is constantly changing.
· Sedimentary rocks are created by sediment being deposited on top of each other and then pressed and cemented together. The oldest layer is the layer on the bottom.
· Scientists use tools to take core samples of what is under the surface of Earth.
Safety Issues
Check for food allergies before making or purchasing the layer cake.
Teacher Background
This 2 day lesson will explore how sedimentary rocks are formed. The lesson will stress that compaction and cementation are part of the process of the formation of sedimentary rock. The lesson will also cover that fossils are found in sedimentary rock and that the oldest layer of rock is the bottom layer.
When rocks and minerals on the surface of Earth’s crust are exposed to wind and rain or heating and freezing, they naturally weaken and break apart to form sediments. This process is called weathering. These materials may then later be carried away and deposited as sediments at the bottoms of rivers and streams, or near the places where rivers empty into large bodies of water. This process which carries the sediments away is called erosion. Sedimentary rocks form when these sediments are squeezed and cemented together under the weight of accumulated material. Sedimentary rock layers are deposited in sequence, with the oldest layer at the bottom and the youngest layer at the top. By looking at sedimentary rock layers, we can tell what happened to the sediments in a specific area and what kinds of plants and animals lived there long ago.
Compaction occurs after the sediments have been deposited. The weight of the sediments squeezes the particles together. When more and more sediments are deposited on top, the weight on the sediments below increases. Waterborne sediments become so tightly squeezed together that most of the water is pushed out.
Cementation happens when dissolved minerals fill in the spaces between the sediment particles. These liquid minerals act as glue or cement to bind the sediments together.
Trying to see what is beneath the surface of Earth is one of the jobs of a geologist. Rather than digging up vast tracts of land to expose an oil field or to find some coal, core samples can be taken and analyzed to determine the likely composition of Earth’s interior.
Sedimentary rocks are important because fossils and fossil fuels are found in them.
Throughout these lessons you will be reminding students of the collaboration protocols that you are working on. This should be a skill like listening, disagreeing appropriately, engaging all participants, etc. There is more information in the Introduction section of your grade level science curriculum on iXplore.
NGSS Crosscutting Concepts:
Patterns. Observed patterns of forms and events guide organization and classification, and they prompt questions about relationships and the factors that influence them.
Day 1
ENGAGE Time: 5 minutesActivities/Events
Teacher Directions / Guiding Questions
1. Show the students the cliff picture and a Snickers bar that has been cut in half.
2. Have the students turn and talk to their partner about how the two are similar. / · How are the two similar? (They both have layers.)
· Do all the layers look the same? (No.)
· What is different about the layers? (Possible answers may include color, thickness, and materials of the layers.)
EXPLORE Time: 45 minutes
Activities/Events
Teacher Directions / Guiding Questions
1. Review with the class the protocol for working in a group and taking turns. Make sure to remind the students to monitor themselves on the protocol while completing the activity.
2. Give each group of students a Ziploc baggie to store their findings in while on their walk.
3. Take the students on a walk outside asking them to pick up various sized pieces of rock, dirt, or mud that they may see. (Have the students look in the dirt and on the playground). As you are walking the class around looking for various sizes of rocks make sure to collect or have sand available. They may also collect pieces of plants or wood that they find interesting.
4. As a groups have the students choose the most interesting pieces. Make sure to include all different sizes of particles to combine together.
5. Each group will fill a small paper cup (bathroom size Dixie cup) about ¼ full with the pieces they choose.
6. Have a student place another Dixie cup inside their cup and press down on their mixture. Take out the extra Dixie cup and place it aside.
7. Take liquid glue and add enough glue in the cup to make sure that all the pieces have glue all over it (be careful not to use too much or it won’t dry in time).
8. With a craft stick, mix the contents and the glue together.
9. Have students repeat Step 6.
10. Allow the glue to dry overnight. / · What do the various pieces of materials that were collected represent? (Sediments that were formed from rocks that were weathered away.)
EXPLAIN Time: 25 minutes
1. Place a sedimentator in the middle of each table. Have the students shake the sedimentator and place it back in the middle of the table.
2. Explain that the settling they observed can be compared to the way that sediments settle when sedimentary rocks are formed. Let the sedimentators sit on a shelf for several days to show true sedimentation.
3. Show the video on how sediments are deposited. http://www.classzone.com/books/earth_science/terc/content/visualizations/es0604/es0604page01.cfm?chapter_no=visualization
4. Have the students read pages 108-109 of the National Geographic Earth Science book with a partner.
5. Ask, “What processes are needed to form sedimentary rock?
6. Discuss cementation. Show animation to help students understand. http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page02_popup5.cfm
7. Explain that sedimentary rocks become hardened when thick piles of sediment accumulate in layers that are later buried deep within the Earth’s crust. They become compacted with the weight of the layers above and all the water is squeezed out of the spaces between the grains. Certain minerals that are dissolved in the water are left behind and act as a type of cement, bonding the loose grains together to form a sedimentary rock. Discuss where these sedimentary rocks might be found on Earth (the ocean floor, ancient riverbeds, lakes, canyons and deltas).
8. Close the lesson by showing the Sedimentary Rock Formation slide and have the students use the words on the slide to describe in their science notebooks how sedimentary rocks are formed. / · Which layer appears to have settled to the bottom first? Why? (The gravel should settle first because it is heavier.)
· What do you notice about the rest of the layers? Is there a pattern to how the sediments settle? (Students should note that the particles of sediments get smaller/finer as the layers progress from bottom to top.)
· What processes are needed to form sedimentary rock? (compaction or pressure and cementation)
· What process did pressing down on the sediments represent in the Explore stage? (compaction)
· What does the glue represent in the Explore stage? (cementation and time necessary for the various sediments to stick together.)
· What would happen if time were not allowed for the glue in your cup to dry? (The sediment pieces would not stick together, which would not allow a sedimentary rock to form.)
· Why can fossils be found in sedimentary rocks? (When a living thing dies a fossil can be left behind in a layer of rock. More sediments pile up allowing pressure to force all the parts together to become one large rock.)
Day 2
EXPLAIN Time: 20 minutesActivities/Events
Teacher Directions / Guiding Questions
1. Explain that geologists look at the
characteristics of rocks to learn about the
environment where the rock was formed.
Before the layers were compacted and
cemented into rock layers, they were
sediment layers.
2. Provide each table with one type of
sediment that they are going to add to
the class sedimentation jar (1L plastic
bottle). Have students use hand lenses
to observe the sediments up close so
they can share its properties with the
class. Call each table up one at a time
to add their sediments to the jar. Have
them share with the class the
characteristics of the sediment they have
(color, texture, etc). Use the guiding
questions to keep the class engaged as
the jar is being filled.
3. Create an anchor chart on sedimentary
rocks. Make sure you include a sketch of
the class sedimentation jar along with
labels that show the oldest and youngest
layer.
4. At this time, have the students work with
a partner to read and highlight the
information about sedimentary rocks on
page 75 in their study guide.
5. Add the words cementation and compaction to their science notebook. This would be a good place to do a VKV (Visual Kinesthetic Vocabulary) for these words. See the video in the Foldables folder on the G drive. / · What are sediments? (sand, soil, mud, pebbles, etc.)
· Name some characteristics of the sediment you are adding to the jar. (answers vary)
· Why do sedimentary rocks have layers? (Sediments are deposited in layers and when the layers are pressed together they are preserved in layers.)
· Which layer has been in the jar for the longest time? (the bottom layer)
· Is your layer older or younger than the layer below it? (Younger, older layers are below younger layers so the youngest layer is always on top and the oldest is on bottom. A good way to explain this is to ask students if after they deposited the first layer in the jar would they be able to put their layer underneath it. The answer is no, unless you come up with some extravagant method. The same is true in nature. Once a layer is deposited, the next layer has to go on top. That’s how you know that the older layers are below younger layers.)
ELABORATE Time: 45 minutes
Activities/Events
Teacher Directions / Guiding Questions
1. Explain that scientists use different methods to study layers of sediment that are below Earth’s surface.
2. Tell the students that we are going to use a model of Earth to think about how we can see sediment layers that aren’t visible at the surface of Earth. Explain that the cake represents just a shallow part of the crust of Earth. You could tell them that it represents the ground underneath the school to help them picture the model. The layers we are talking about here are layers of sedimentary rock which are found all over Earth’s surface.
3. Show the students the cake and ask, “How can you learn about what is inside this cake without cutting it open or removing the frosting?” Have the students brainstorm ideas as a Think, Pair, Share activity.
4. List all ideas on the board and discuss pros and cons of each.
5. Give each pair of students a straw. Each group will push the straw into the cake and pull it back out. They should be able to see all the layers if they push it down to the bottom, but the layers will be compressed.
6. Have the students draw their core sample in their science notebook using the correct colors to show layers. Make sure they remember to draw the core in the correct orientation. (Students tend to hold the core sample upside down so the cake doesn’t come out the bottom. Use the frosting as a guide for them to remember which side is the top.)
7. Have the students label the oldest and youngest layers on their drawing.
8. Have students read about Joaquin Ruiz, a Geochemist in the Cool Careers in Earth Sciences book, pages 14-15. / · How do we learn about sedimentary layers that are covered up? For example, how do you know what the layers look like under your school? Or under the ocean? (Scientists use tools, like echosounders, to image sedimentary layers. They also take sediment cores to collect a tube of sediment layers beneath Earth’s surface.)
EVALUATE Time: 10 minutes
Activities/Events
Teacher Directions / Assessment
1. Show the rock layers diagram and have the students explain which layer is the oldest and how they know it is the oldest. / · Exit Ticket
SCIE_5_A_Les42Sedimentary Rocks_LES2014 CFISD