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Title: The Rock Cycle
Principle(s) Investigated: Simulate the rock cycle by creating sedimentary, metamorphic and igneous rocks.
Standards : California Science Standards
7th Grade Earth and Life History (Earth Sciences)
4. Evidence from rocks allows us to understand the evolution of life on Earth. As a basis for understanding this concept:
a. Students know Earth processes today are similar to those that occurred in the past and slow geologic processes have large cumulative effects over long periods of time.
c. Students know that the rock cycle includes the formation of new sediment and rocks and that rocks are often found in layers, with the oldest generally on the bottom.
California Science Standards Grades 9-12, Earth Science
Dynamic Earth Processes
c. Students know how to explain the properties of rocks based on the physical and chemical conditions in which they formed, including plate tectonic processes.
Materials: Chocolate Chips or Crayons (3 different colors)
Plastic Knives
Pencil Sharpeners
Zip Lock Bags
HEAVY Aluminum Foil
Paper Cups/ Bowls
Ice Cubes
Hot Plate
Tongs
Procedure:
Part 1: Weathering
1.Before the lab begins review how each of the rocks are formed; sedimentary, metamorphic and igneous. Review weathering and the effects on rocks such as water and wind.
2.Students review the materials within their group. Students answer 3 questions about weathering; 1. In this model what will represent the rocks? 2. What will represent weathering? 3. What are some real life examples of weathering?
3.Students begin to weather the chips or crayons. Use the pencil sharpener to weather the crayons and place each color in a separate cup. Use the plastic knife to grate the chips and place the shavings in small cups.
4.Answer question: When a rock has weathered are all the size fragments the same? Explain using the chips.
Part 2: Making a Sedimentary Rock
1.Review the definition of a sedimentary rock, how it forms and some real life examples.
2.Students layer the chip shavings, or crayon shaving onto the sheet of aluminum foil. They then fold into a packet and apply pressure with hands. Students then unfold their packet and describe the changes they see.
3.Answer questions: Is the rock compacted in tight layers or lose layers? Can you see the different size chips?
4.Set aside a small piece of the sedimentary rock.
Part 3: Making a Metamorphic Rock
1.Review the definition of a metamorphic rock, how it forms and some real life examples.
2.Students wrap their chip shavings back into a packet.
3.Put the packet on the ground and stand on it for 1 minute, applying more heat and pressure.
4.Answer questions: Can you see the different size chips? Are the layers as visible as the sedimentary rock?
5. Set aside a small piece of the metamorphic rock.
Part 4: Making an igneous Rock
1.Review the definition of an igneous rock, how it forms and some real life examples.
2.Students wrap their chip shavings back into a packet.
3. Place the packet on a hot plate for about 2 minutes.
4. Pour the melted rock into a small cup that is on top of a bow. The bowl has ice surrounding it to cool the rock.
5.Once the rock has cooled, describe the igneous rock.
Extension Activities:
Rock Cycle Song
By: J Michael, Manhattan Beach USD
(Tune of “Row, Row, Row Your Boat”)
SEDI-MEN-TARY rock
Has been formed in layers
Often found near water sources
With fossils from decayers
Then there’s IGNEOUS rocks
Here since Earth was born
Molten Lava, cooled and hardened
That’s how it is formed
These two types of rocks
Can also be transformed
With pressure, heat and chemicals
META-MORPHIC they’ll become
Create a Short Story
Students can make their own story for their rock that goes through the rock cycle.
Student prior knowledge: Before beginning this lab the teacher must determine what the students already know about the rock cycle. The teacher can ask about a cycle and students can complete a bubble map or thinking map based on their previous experience. Possible answers can include the carbon and water cycle. The teacher can then ask the students about previous models used in the science classroom such as the Solar System. After the class has brainstormed about a cycle and model the teacher can introduce the topic of the rock cycle. Students can complete a KWL chart, about what they know, what they want to know and at the end of the lesson what they learned about the rock cycle. Students should have knowledge of how rocks are classified into three major groups (sedimentary, metamorphic and igneous). Students understand that environmental factors such as erosion and weathering can contribute to the appearance of rocks.
Explanation: This lesson is for middle school students in sixth
and seventh grade. However in high school there are California Science Standards for students in ninth- twelfth grade. For those students I would expand the assignment in the following ways. Students would have more advanced lessons that could include the following; fractional crystallization, describing grain texture and metamorphism. The teacher can provide actual examples of igneous rock textures such as coarse – grained, fine-grained, porphyritic, glassy and vesicular. For the chocolate lab, the teacher can provide the students with other materials to model these types of rocks. This lesson can be linked to writing by having the secondary students write a report on a specific rock, where it is found and their own model of the rock. Students can bring in rock samples to discuss their findings.
Questions & Answers:
1. What are the three main types of rocks and definitions?
Sedimentary- made from loose fragments of rock, minerals and organic material that results from the physical breakdown of rocks which is sediment, many sedimentary rocks are made up of different combinations of sediment.
Metamorphic-process by which heat, pressure or chemical processes change one type of rock to another
Igneous- “from fire,” form when magma cools and hardens
2. What is the difference between compaction and cementation in sedimentary rocks?
Compaction is the process in which sediment is squeezed and the size of the pore space between sediment grains is reduced by the weight and pressure of overlying layers. Cementation is the process in which sediment are glued together by minerals that are deposited in water.
3. What is the difference between fine-grained and coarse grained igneous rocks?
Coarse grained igneous rocks have large mineral crystals which are formed from the slow loss of heat. These large crystals are described as coarse grained texture, some examples include granite. Fine grained textured igneous rocks are composed of small mineral grains. An example is basalt.
Applications to Everyday Life: The rock cycle is important because it provides a basis for understanding the properties of different types of rocks. One application of the rock cycle is to Bowen’s reaction series. As stated in Holt, “Bowen’s hypothesis, minerals form in two ways; gradual, continuous formation on minerals that have similar chemical compositions and the second way by sudden changes in mineral types” (Holt, 127). Different minerals crystallize at different times during the solidification of magma. The rock cycle can also be used to explain organic limestone formation. Organisms that live in oceans take chemicals from the water and produce the mineral calcium carbonate. This is used to build their shells or skeletons. When the organism dies the shell or skeleton settle to the ocean floor. The shells of the dead organisms pile up and eventually the layers are compacted to form limestone. This relates to the rock cycle, since this is an example of an organic sedimentary rock. A final example includes nonfoliated rock such as marble that is seen within the Parthenon in Greece. The Parthenon has been “standing in Greece for more than 1,400 years” (Holt, 144). The calcium carbonate found within the marble is susceptible to chemical weathering through acid rain.
Photographs:
Videos:
References: Allison, Mead, Arthur DeGaetano, and Jay Pasachoff. Earth Science. Orlando:
Holt, Rinehart and Winston, 2007. Print. 1-937
Gere, Nicholas. "The Rock Cycle." Rocks For Kids. N.p., 2011. Web. 5 Dec. 2011.
Herr, Norman. The Sourcebook for Teaching Science. San Francisco: Jossey- Bass,
2008. Print. 1-584
Michaels, Jennifer. "Geology is Sweet." California Science Teachers Conference .
Pasadena , CA . 20 Oct. 2011. Class presentation.
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