Georgia Performance Standards Framework for Earth Science Grade 6

Transcription

1 The following instructional plan is part of a GaDOE collection of Unit Frameworks, Performance Tasks, examples of Student Work, and Teacher Commentary. Many more GaDOE approved instructional plans are available by using the Search Standards feature located on GeorgiaStandards.Org. Unit: Rocks and Minerals General Task How are Minerals Used to Help Identify Rocks? (Recommended as an extension or for use with students who have mastered classifying rocks by their process of formation) Standards (Content and Characteristics): S6E5. Students will investigate the scientific view of how the earth s surface is formed. b. Investigate the contribution of minerals to rock composition. c. Classify rocks by their process of formation. d. Describe processes that change rocks and the surface of the earth. S6CS1. Students will explore the importance of curiosity, honesty, openness, and skepticism in science and will exhibit these traits in their own efforts to understand how the world works. a. Understand the importance of and keep honest, clear, and accurate records in science. S6CS6. Students will communicate scientific ideas and activities clearly. c. Organize scientific information using appropriate tables, charts, and graphs, and identify relationships they reveal. S6CS2. Students will use standard safety practices for all classroom laboratory and field investigations. a. Follow correct procedures for use of scientific apparatus. b. Demonstrate appropriate techniques in all laboratory situations. c. Follow correct protocol for identifying and reporting safety problems and violations Enduring Understanding: Rocks are classified based on how they formed and their mineral composition Sedimentary rocks are formed by the ongoing deposition of rocks and other sediments that are cemented together. Rocks at the Earth s surface weather, forming sediments that are buried, then compacted, heated, and often re-crystallized into new rock.

2 Essential Questions: How are rocks formed? How are rocks classified? One Stop Shop For Educators Pre-Assessment: ADMINISTRATION PROCEDURES Put rocks at various stations. Ask students to identify the rocks. Provide students with a blank answer document to record responses. Students will move from station to station and identify as many rocks as possible using visual observations. Outcome / Performance Expectations: General Teacher Instructions: Materials Needed: Students will be able to identify common igneous, sedimentary, and metamorphic rocks. Students will identify the minerals present in rocks. Students will interpret the process of formation of rocks by looking at their textures. Obtain mineral and rock specimens from scientific supply house, from gem and mineral show, or by collecting them. Local mineral societies may also have materials which they can donate. Set out the following minerals with names labeled for this exercise. Students should be able to refer to these specimens to assist them with identifying the rocks they will see in this exercise. Quartz Feldspar Muscovite Biotite Calcite Gypsum Kaolinite (sometimes called kaolin) Rocks that the students will identify should include the following IGNEOUS ROCKS: Granite Gabbro Diorite Basalt Rhyolite Andesite Pumice Scoria Obsidian July 26, 2007 Page 2 of 11

3 SEDIMENTARY ROCKS: Sandstone Shale Limestone Rock gypsum Conglomerate Breccia METAMORPHIC ROCKS: Slate schist Mica Gneiss Marble Quartzite Mineral identification tools, to include: glass (could be a small glass jar or rectangular piece of glass with edges covered in masking tape to protect fingers), steel nail, copper penny, and your fingernail. Magnifying glass, or stereozoom digital microscope (biologists may call this a dissecting microscope). Microscope is optional. At the least, provide magnifying glasses. It is suggested that a small dropper bottle of hydrochloric acid be available so that the teacher can demonstrate the use of acid to identify minerals. With proper safety instruction, splash-proof goggles, and nitrile gloves, students may use the acid under supervision. If there are safety concerns, the acid test may be considered as an optional part of this task. Splash resistant safety goggles, nitrile (or rubber) gloves if acid will be used. Safety Precautions: Hydrochloric acid may be purchased from a scientific supply house or obtained as muriatic acid from a hardware store. Concentration should be about 10% (one part acid to ten parts water). Always add acid to water. Never add water to acid. Dilute hydrochloric acid (HCl) is used to identify minerals. The teacher will demonstrate proper use of HCl by wearing splash-proof goggles and protective gloves (nitrile or rubber gloves are recommended). Apply one drop of HCl from the dropper bottle and observe for reaction. With proper safety instruction, splash-proof goggles, and nitrile gloves, students may use the acid under supervision. If there are safety concerns, the acid test may be considered as an optional part of this task for students. Please use care in handling acid. Do not allow to contact skin, eyes, clothing, etc. Acid will make holes in cloth and cause metal to rust. Do not get acid near computers or other equipment with metal or electronic parts. Wear splash- July 26, 2007 Page 3 of 11

4 resistant safety goggles and protective gloves (nitrile gloves are recommended). Do not use concentrated acid. When diluting, always add acid to water. Never add water to acid. Task with Student Directions: Wash hands (and any items that touched the acid) thoroughly after using acid. Wash acid from mineral specimens. Do not allow acid to stand on the samples or in the sample box. Wipe up all spills promptly. Do not breathe acid vapors. Use of acid may be hazardous to those with certain medical conditions. Please remember that acid is a hazardous material and follow any package directions carefully. Check MSDS for additional information. Rocks A rock is an aggregate of one or more minerals. There are three basic categories of rocks: Igneous (or cooled from hot molten lava or magma) - ex. granite, basalt Sedimentary (or fragments laid down by water or wind) - ex. sandstone, shale, limestone Metamorphic (or rocks changed by heat and or pressure) - ex. gneiss, schist, slate, marble Rocks are the building blocks of the Earth's crust. We can identify the minerals present in rocks. We can learn about the process of formation of rocks by looking at their textures (or grain sizes, shapes, and arrangement). I. IGNEOUS ROCKS Igneous rocks are "fire-formed". They crystallized from hot, molten lava or magma as it cooled. Magma is hot, molten rock beneath the surface of the Earth. Lava is hot, molten rock which has flowed out onto the surface of the Earth. Magma may cool within the Earth's crust to form igneous rocks. But lava cools much more quickly because it is on the Earth's surface where temperatures are much lower than they are deep within the Earth. Cooling rates influence the texture of the igneous rock: Quick cooling = fine grains Slow cooling = coarse grains July 26, 2007 Page 4 of 11

5 Igneous rocks are classified (or named) based on their composition (which minerals they contain) and texture (or the size of the mineral grains). The texture is a result of the process of formation of the igneous rocks. A variety of textures are present in igneous rocks. For this exercise, we will only consider a few textures (and their process of formation): Fine-grained (produced by quick cooling and crystallization of lava) Coarse-grained (produced by slow cooling and crystallization of lava) Glassy (produced by instantaneous cooling of lava so fast that there is no time for minerals to crystallize) Vesicular (contains holes made by gas bubbles in a quick-cooling or instantaneous-cooling lava) Now and then, you may see an igneous rock with a mixture of grain sizes larger minerals surrounded by smaller minerals. This indicates a complicated process of formation of the igneous rock, in which the magma initially cooled very slowly, and then the magma erupted as lava and cooled quickly. An igneous rock with mixed grain size indicates a mixed cooling history. Part A. Examining the minerals in coarse-grained igneous rocks. Examine granite, diorite and gabbro with the magnifying glass or microscope. Describe the appearance of at least two minerals you can see in each rock. Can you identify any of the minerals (from the list of those you looked at previously?) Igneous Rock Granite Describe two minerals using their physical properties Identify these minerals Diorite Gabbro July 26, 2007 Page 5 of 11

6 Part B. Examining the minerals and textures of igneous rocks. Examine the igneous rocks listed in the table below. Tell whether their minerals are visible and readily seen with the naked eye (coarse grained), or whether they are too small to identify (fine grained), or whether the texture is glassy, vesicular (bubbles) or mixed. Then interpret the process of formation of the igneous rock. Igneous Rock Obsidian Pumice Scoria Granite Rhyolite Diorite Andesite Basalt Gabbro Texture (fine-grained, coarsegrained, glassy, vesicular, or mixed) Process of formation (fast cooling, slow cooling, instantaneous cooling, gas bubbles released during cooling, or mixed cooling history) II. SEDIMENTARY ROCKS Sedimentary rocks are made from sediment. Sediment is loose particulate material (clay, sand, gravel, shells, plant fragments, etc.). Sediment may be transported and deposited by moving water, wind, or ice. Sediment becomes compacted and cemented to form sedimentary rock. July 26, 2007 Page 6 of 11

7 We can interpret the process of formation of sedimentary rocks by looking at their grain size and shape (i.e., their texture). Fine-grained sedimentary rocks were deposited by still, quiet, low-energy water. Coarse-grained sedimentary rocks were deposited by rapidly-moving, high-energy water. We can also look at the shapes of the grains in sedimentary rocks to learn about their process of formation. Rounded grains in a sedimentary rock indicate a long distance of transportation during which the grains of sediment rolled and tumbled along, which wore down any sharp corners. Angular grains in a sedimentary rock indicate a short distance of transportation. Part A. Examining the minerals in sedimentary rocks. Examine the sedimentary rocks listed in the table below. Use a magnifying glass. Do tests to identify the minerals. Write the names of the minerals present beside each rock name in the table below. Answer the questions below. Sedimentary rock Sandstone Mineral(s) present Limestone Rock gypsum Shale Which of these rocks contains calcite, the mineral that fizzes in hydrochloric acid? Test them and see. Which of these rocks contains gypsum, the mineral that you can scratch with your fingernail? Which of these rocks contains clay minerals? Which of these rocks contains quartz, a mineral that scratches glass? July 26, 2007 Page 7 of 11

8 Part B. Examining the textures of sedimentary rocks Examine the sedimentary rocks listed in the table below. Use a magnifying glass. Describe the grain size and then interpret the process of formation, indicating whether it was deposited by high-energy or low-energy water. Then in the next table, examine the differences in grain shape in conglomerate and breccia, and interpret the process of formation in terms of distance of transport. Sedimentary rock Conglomerate Sandstone Shale Breccia Grain size (fine-grained or coarsegrained) Process of formation (deposition by highenergy or low-energy water) Sedimentary rock Conglomerate Breccia Grain shape (angular or rounded) Process of formation (long or short distance of transport) III. METAMORPHIC ROCKS Metamorphic rocks formed as a result of changes to other types of rocks. The processes of formation of metamorphic rocks involve changes caused by heat and pressure associated with deep burial and tectonic pressures (caused by moving tectonic plates). Those changes, called metamorphism, include compaction (which makes the rock become more dense and makes the grains move closer together), and re-crystallization (the growth of new minerals). In other words, metamorphism causes changes in the texture and minerals of rocks. July 26, 2007 Page 8 of 11

9 As shale is subjected to increasing heat and pressures, the clay minerals in it are re-crystallized to form micas (such as muscovite and biotite). As heat and pressure increase, the mica grains increase in size. Pressure causes the minerals in a metamorphic rock to become oriented perpendicular to the direction of force. The mica grains (such as muscovite and biotite) become aligned parallel with one another to form a new texture called foliation. Rocks with foliation include slate, schist and gneiss. Metamorphic rocks which lack mica minerals are called non-foliated, and they have an even, granular texture with no aligned minerals. Non-foliated metamorphic rocks include marble and quartzite. Part A. Examining minerals in metamorphic rocks. Examine the metamorphic rocks listed in the table below. Use a magnifying glass. Do tests to identify the minerals. Write the names of the minerals present beside each rock name in the table below. Answer the questions below to help you. Metamorphic rock Mineral(s) present Slate Schist Gneiss Marble Quartzite Which of these rocks contains calcite, the mineral that fizzes in hydrochloric acid? Test them and see. Which of these rocks contain(s) mica (muscovite and/or biotite)? Which of these rocks contain(s) quartz, a mineral that scratches glass? July 26, 2007 Page 9 of 11

10 Which of these rocks is very fine grained and looks most like it might have formed from clay minerals? Part B. Examining textures in metamorphic rocks. Examine the metamorphic rocks listed in the table below. Use a magnifying glass. Look at the textures to determine if the rocks are foliated or nonfoliated. Metamorphic rock Texture (foliated or non-foliated) Gneiss Marble Schist Quartzite Slate Resources: /es0505page01.cfm?chapter_no=visualization The Georgia Mineral Society provides mini-grants for teachers to assist with the purchase of rocks and minerals. See The Georgia Mineral Society has a list of retired hobbyist and working professionals who have agreed to give talks on subjects related to our hobby. Interested parties may contact GMS at gmsmail@gamineral.org and request a speaker. GMS speakers will review and fulfill these requests as their individual schedules permit! Learn more about our GMS Speakers Bureau by following this link: July 26, 2007 Page 10 of 11

11 Homework / Extension: Instructional Task Accommodations for ELL Students: Instructional Task Accommodations for Students with Specific Disabilities: Instructional Task Accommodations for Gifted Students: Plan a fieldtrip to a local museum that has displays of minerals and rocks, such as the Weinmann Mineral Museum (TELLUS) in Cartersville. Identify and locate information on your home state's (or a nearby state's) state mineral. You can learn about the state mineral, state gem, and state fossil on this web page. See also Work with a student with strong English language skills Highlight key points in the article Reduce the number of key points these students are responsible for knowing Extend the time to complete the task Seat student near teacher or positive role model during direct instruction and student centered activity time Adjust teacher talk to increase comprehensibility during direct instruction and while conveying task directions Speak carefully and avoid slang terms or unfamiliar idiomatic experience Describe the characteristics of the rocks for visually impaired students Break work into manageable parts Reinforce oral instructions with written instructions Graphically display an analysis of the expected task including a checklist to facilitate attention to task and organizational skills Assess informally on an on-going basis Use alternative assessments Have gifted students use rock identification keys from the web or from a book to identify minerals and rocks. Give them unlabeled rocks to identify. Provide digital microscopes to examine the rocks. Have the gifted students take digital images of the rocks and prepare a computer presentation for the class indicating how each of the rocks formed. Allow role plays and scenarios. Offer choices and chunk concepts for students. Problem-based Learning Activities. July 26, 2007 Page 11 of 11