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Soil Lessons: Science Society America Demonstrating Mechanical and Chemical Materials Needed Weathering using Crackers Dig Crackers (enough to have one per student) Deeper in rocks and the salt is left behind when the evaporates. As the salt grow, they push the further and further apart. Chemical weathering involves a change in the chemical composition of the rocks. There are three main types of chemical weathering: Dissolution, Oxidation and . Dissolution occurs when acidic dissolve rock formations. Oxidation is a process similar to rusting in which the found in rocks becomes oxidized. Hydrolysis causes the weathering of into clays. Vocabulary* Summary Erode (): To wear away, or remove, rock or soil particles by water, , and/or In this activity, students will learn the dif- ference between mechanical and chemical (Weathering): To break down rocks weather. and minerals at or near ’s surface into smaller particles and soil Chemical Weathering: The breaking down Background Information of rocks by changing the chemical composi- tion of the rocks Weathering is a process that helps shape Mechanical Weathering: The breaking down the Earth’s surface. It affects rocks in of rocks by physical means place and does not involve the movement *from www..4teachers.org glossary of materials to other locations. This is what distinguishes weathering from erosion. There are two types of weathering: me- Methods/Procedure chanical and chemical. Simply put, me- 1. Give each student a cracker. chanical weathering is the breaking down of 2. To demonstrate mechanical weathering, rocks into smaller pieces. With mechanical use your hands to break the crackers into weathering, the composition of the rocks smaller pieces. Record observations in does not change. There are several types your science journal. of mechanical weathering. Freeze-thaw occurs when liquid water seeps into cracks 3. To demonstrate chemical weathering, in the rocks and then freezes and expands. put the cracker pieces in your mouth and This expansion causes the cracks to grow chew but DO NOT swallow. Record obser- and the rock to break apart. Another way vations in your science journal. mechanical weathering can take place is by Notes shrink-swell. As rocks heat up, they expand If you cannot use food items in your class- and then shrink as they cool. This process room, this lab can be done using antacid can cause the rock to again break down into tablets instead of crackers and a cup of smaller pieces. Salt can also cause mechani- water instead of your mouth. cal weathering. Salt water can fill cracks Committee Member. Teacher andSoilScienceSocietyof America K12 Author: weathering.html versity: http://www.ux1.eiu.edu/~cfjps/1300/ March 26).Retrieved fromEasternIllinoisUni Mechanical andChemicalWeathering weathering/?ar_a=1 tionalgeographic.com/education/encyclopedia/ Geographic Education:http://education.na March 26). McDaniel ,M.,Ramroop T., . Teng, S. Boudreau, D.,Costa,H.,Hall,Hunt,J., science.org/ tion ScienceStandards:http://www.nextgen Science Standards Achieve, Inc. Sources 1.  Conclusion Questions 4.  3.  2.  1.  Analysis Questions Demonstrating Mechanical&ChemicalWeathering Soil Lessons:ScienceSociety America www.soils4teachers.org Additional Resources surface. applied toactualrocksontheEarth’s why not? weathering wasitstillacracker?Whyor weathering. went throughtheprocessofchemical or whynot? cal weatheringwasitstillacracker?Why weathering. went throughtheprocessofmechanical Explain howthisdemonstrationcanbe When thecrackerwentthroughchemical Explain whathappenedwhenthecracker When thecrackerwentthroughmechani Explain whathappenedwhenthecracker JuliaLieberman,MiddleSchoolScience Weathering. (2014,March26). . Retrieved fromNextGenera Retrieved fromNational Next Generation . (2014, (2014, - - - - -

2-ESS1-1. HS-ESS2-5. HS-ESS2-1. MS-ESS3-1 MS-ESS2-1. MS-ESS2-2 5-ESS2-1. 4-ESS2-1. 2-ESS2-1. • • • • • • • • • • • • • • Water effects Earth’s materialsandsurfacesprocesses Earth’s resources are limitedandunevenlydistributed. Earth’s materialsmoveinacycle. can belarge orsmall. Different processes changetheEarth’s surfaceattimeandspatial scalesthat ways. The geosphere, , hydrosphere, andatmosphere interactinvarious Water, ice,windandvegetationeffect theratesofweatheringanderosion. Solutions canbedevelopedtosloworprevent changesinthelandscape. Earth eventscanoccurquicklyorslowly. How doeswatereffect Earth’s materialsandsurfaceprocesses? Why are theEarth’s resources limitedandunevenlydistributed? What processes shapetheEarth’s surface? How dothegeosphere, biosphere, hydrosphere, andatmosphere interact? and vegetation? How are theratesofweatheringanderosion effected bywind,ice,water, How canchangesinthelandscapebeslowedorprevented? 2nd grade|4th5thMiddleSchoolHighSchool   . .

result of pastandcurrent geoscienceprocesses. distributions ofEarth’s ,energy, andgroundwater resources are the energy thatdrivesthisprocess. have changedEarth’s surface atvaryingtimeandspatialscales. biosphere, hydrosphere, and/oratmosphere interact. of weathering ortherateoferosion bywater, ice,,orvegetation. changing theshapeofland. Compare multiple solutionsdesignedto sloworprevent wind orwaterfrom events can occurquicklyorslowly. Use informationfrom severalsources toprovide evidencethat Earth Earth materialsandsurfaceprocesses. -floor features. operate atdifferent spatialand temporalscales toformcontinentaland Develop amodeltoillustratehow Earth’s andsurfaceprocesses internal Construct ascientificexplanationbasedonevidenceforhow theuneven Develop amodeltodescribe thecyclingof Earth’s materialsandtheflowof Construct anexplanationbasedonevidenceforhow geoscienceprocesses Plan andconductaninvestigationof theproperties of wateranditseffects on Develop amodelusinganexampletodescribe waysthegeosphere, Make observationsand/ormeasurements toprovide evidenceof theeffects Next GenerationScienceStandards Enduring Understandings Essential Questions www.soils.org Soil ScienceSocietyof America

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