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Eighth Grade Science Introduction This book belongs to: ______________________________________ CREDITS Unless otherwise noted, the contents of this book are licensed under the Creative Commons Attribution NonCommercial ShareAlike license. Detailed information about the license is available online at http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode. Prior to making this book publicly available, we have reviewed its contents extensively to determine the correct ownership of the material and obtain the appropriate licenses to make the material available. We will promptly remove any material that is determined to be infringing on the rights of others. If you believe that a portion of this book infringes another’s copyright, contact Assistant Superintendent of Curriculum and Instruction. If you do not include an electronic signature with your claim, you may be asked to send or fax a follow-up copy with a signature. To file the notification, you must be either the copyright owner of the work or an individual authorized to act on behalf of the copyright owner. Your notification must include: 1. Identification of the copyrighted work, or in the case of multiple works at the same location, a representative list of such works at that site. 2. Identification of the material that is claimed to be infringing or to be the subject of infringing activity. You must include sufficient information, such as a specific page number or other specific identification, for us to locate the material. 3. Information for us to be able to contact the claimant (e.g., email, address, phone number). 4. A statement that the claimant believes that the use of the material has not been authorized by the copyright owner or an authorized agent. 5. A statement that the information in the notification is accurate and that the claimant is, or is authorized to act on behalf of, the copyright owner. This book is adapted from the excellent materials created by the CK-12 Foundation (http://ck12.org) which are licensed under the Creative Commons Attribution NonCommercial ShareAlike license. We express our gratitude to the CK-12 Foundation for their pioneering work on secondary science textbooks, without which the current book would not be possible. We would like to thank Utah’s State Department of Education for providing a model for Broken Arrow Public Schools. We also thank the amazing Broken Arrow Public Schools’ (BAPS) 8th Grade Science teachers whose collaborative efforts made the book possible. We also extend our appreciation to Skiatook Public Schools’ 8th Grade Science Teacher Angela Shoemate and for her contributions. This textbook is aligned with Oklahoma Academic Standards, BAPS and SPS Sequence of Instruction for 8th grade. Thank you for your commitment to science education! TABLE OF CONTENTS Chapter 1 Chemical Reactions 1.1 Chemical Reactions (MS-PS1-5) Page 4 1.2 Conservation of Mass (MS-PS1-5) Page 7 1.3 Endothermic and Exothermic Reactions (MS-PS1-6) Page 10 1.4 Chemical Reactions and Food (MS-LS1-7) Page 16 Chapter 2 Motion and Forces 2.1 Motion and Force (MS-PS2-2) Page 19 2.2 Newton’s First Law (MS-PS2-2) Page 24 2.3 Newton’s Second Law (MS-PS2-2) Page 27 2.4 Newton’s Third Law (MS-PS2-1) Page 30 Chapter 3 Waves 3.1 Waves Basics: Structure and Types (MS-PS4-2) Page 32 3.2 Mechanical Waves and Energy (MS—PS4-1) Page 39 3.3 Electromagnetic Waves (MS-PS4-2) Page 43 3.4 Waves and Transmitting Information (MS-PS4-3) Page 47 Chapter 4 Plate Tectonics 4.1 Earth’s Interior Material (MS-ESS2-2) Page 49 4.2 Early Theories (MS-ESS2-2 and MS-ESS2-3) Page 53 4.3 Theory of Plate Tectonics (MS-ESS2-2 and MS-ESS2-3) Page 58 Chapter 5 Natural Hazards 5.1 Volcanoes (MS-ESS2-2 and MS-ESS3-2) Page 67 5.2 Earthquakes (MS-ESS2-2 and MS-ESS3-2) Page 72 5.3 Caves and Sinkholes/Groundwater Erosion & Deposition (MS-ESS2-2 and MS-ESS3-2) Page 84 5.4 Glaciers and Mass Movement (MS-ESS2-1, MS-ESS2-2 and MS-ESS3-2) Page 87 5.5 Other Natural Hazards (MS-ESS2-2 and MS-ESS3-2) Page 90 Chapter 6 Minerals, Rocks, and the Rock Cycle 6.1 Minerals (MS-ESS2-1) Page 93 6.2 Rocks (MS-ESS2-1) Page 101 6.3 Weathering (MS-ESS2-1 and 2-2) Page 107 6.4 Erosion and Deposition (MS-ESS2-1 and 2-2) Page 111 6.5 Rocks and Processes of the Rock Cycle (MS-ESS2-1) Page 114 Chapter 7 Earth’s History 7.1 Fossils (MS-ESS-1-4, MS-LS4-1, MS-LS4-2) Page 117 7.2 Determining the Rock’s Age (MS-LS4-1) Page 124 7.3 Geological Time Scale (MS-ESS1-4) Page 130 Chapter 8 Human Impact and Resources 8.1 Resources (MS-ESS3-1) Page 133 8.2 Resource Availability (MS-ESS3-1) Page 140 8.3 Resources and Population Growth (MS-ESS3-4) Page 152 8.4 Sustaining and Remediating Resources (MS-ESS3-4) Page 159 8.5 Natural Resources and Synthetic Materials (MS-PS1-3) Page 166 1.1 Chemical Reactions This reading supports… MS-PS1-5: Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved. Chemical Reactions No doubt you’ve seen changes like those pictured in figure to the left. What do all these changes have in common? They are all chemical changes in matter. In a chemical change, matter changes into a different substance with different properties. Chemical changes occur because of chemical reactions. You can see more examples of chemical changes at this URL: http://www.youtube.com/watch?v=66kuhJkQCVM (2:05). What Is a Chemical Reaction? A chemical reaction is a process in which some substances change into different substances. Substances that start a chemical reaction are called reactants. Substances that are produced in the reaction are called products. Reactants and products can be elements or compounds. A chemical reaction can be represented by this general equation: The yield arrow shows the direction in which the reaction occurs. The reaction may occur quickly or slowly. For example, foam shoots out of a fire extinguisher as soon as the lever is pressed. But it might take years for metal to rust. Evidence of Chemical Reactions Not all changes in matter involve chemical reactions. For example, there are no chemical reactions involved in changes of state. When liquid water freezes or evaporates, it is still water. No bonds are broken and no new products are formed. How can you tell whether a change in matter involves a chemical reaction? Often, there is evidence. Four common signs that a chemical reaction has occurred are: Change in color: The products are a different color than the reactants. Change in temperature: Heat is released or absorbed during the reaction. Production of a gas: Gas bubbles are released during the reaction. Production of a solid: A solid settles out of a liquid solution. The solid is called a precipitate. You can see examples of each type of evidence by the figure below and the following URL http://www.youtube.com/watch?v=gs0j1EZJ1Uc (9:57). Breaking and Reforming Chemical Bonds In chemical reactions, bonds break in the reactants and new bonds form in the products. The reactants and products contain the same atoms, but they are rearranged during the reaction. As a result, the atoms are in different combinations in the products than they were in the reactants. Look at the example in figure to the right. It shows how water forms. Bonds break in molecules of hydrogen and oxygen. Then new bonds form in molecules of water. In both reactants and products, there are four hydrogen atoms and two oxygen atoms. But the atoms are combined differently in water. Chemical Reactions Assessments: Essential Skill: Explanations of stability and change in natural or designed systems can be constructed by examining the changes over time and forces at different scales, including the atomic scale. 1. Draw and label an example of a chemical reaction. Be sure to define reactants, products, and yield arrow. (DOK 1) 2. Tina made a "volcano" by pouring vinegar over a "mountain" of baking soda. The wet baking soda bubbled and the temperature decreased. What facts would you select as supporting evidence that a chemical reaction occurred? Besides the evidence seen above, what is other evidence that a chemical reaction occurred? (DOK 3) 1.2 Conservation of Mass By the end of this reading, you should be able to… MS-PS1-5: Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved. This oil-burning power plant is located in the middle of New York City. Its smokestacks are equipped with scrubbers. These are devices that remove many of the pollutants from the exhaust gases. But the smokestacks still release gases. Oil is a fossil fuel. Like all fossil fuels-and the living things from which they form-oil consists mostly of carbon. What happens to the carbon in a fossil fuel like oil when it burns? There doesn’t appear to be anything left from the fire. Is the carbon destroyed in the flames? Actually, the carbon still exists because matter can’t be destroyed. Matter is always conserved in chemical reactions. If you don’t believe it, watch this video: http://safeshare.tv/v/RHOC44LU8Nw Conservation of Mass If you build a campfire like this one, you start with a big pile of logs.
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