Georgia Performance Standards Framework for Physical Science 8 th Grade

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. Subject Area: Physical Science Grade: 8 Standards (Content and Characteristics): S8P1. Students will examine the scientific view of the nature of matter. a. Distinguish between atoms and molecules. b. Describe the difference between pure substances (elements and compounds) and mixtures. e. Distinguish between changes in matter as physical (i.e., physical change) or chemical (development of a gas, formation of precipitate, and change in color). g. Identify and demonstrate the Law of Conservation of Matter. S8P2. Students will be familiar with the forms and transformations of energy. a. Explain energy transformation in terms of the Law of Conservation of Energy. b. Explain the relationship between potential and kinetic energy. S8CS1. 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. b. Understand that hypotheses can be valuable even if they turn out not to be completely accurate. S8CS2. 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. S8CS5. Students will use the ideas of system, model, change, and scale in exploring scientific and technological matters. a. Observe and explain how parts can be related to other parts in a system such as the role of simple machines in complex machines. b. Understand that different models (such as physical replicas, pictures, and analogies) can be used to represent the same thing. June 2008 Page 1 of 8

2 S8CS6. Students will communicate scientific ideas and activities clearly. a. Write clear, step-by-step instructions for conducting scientific investigations, operating a piece of equipment, or following a procedure. b. Write for scientific purposes incorporating information from a circle, bar, or line graph, data tables, diagrams, and symbols. c. Organize scientific information in appropriate tables, charts, and graphs, and identify relationships they reveal. S8CS7. Students will question scientific claims and arguments effectively. a. Question claims based on vague attributions (such as Leading doctors say... ) or on statements made by people outside the area of their particular expertise. b. Identify the flaws of reasoning in arguments that are based on poorly designed research (e.g., facts intermingled with opinion, conclusions based on insufficient evidence). c. Question the value of arguments based on small samples of data, biased samples, or samples for which there was no control. d. Recognize that there may be more than one way to interpret a given set of findings. The Nature of Science S8CS8. Students will be familiar with the characteristics of scientific knowledge and how it is achieved. Students will apply the following to scientific concepts: a. When similar investigations give different results, the scientific challenge is to judge whether the differences are trivial or significant, which often requires further study. Even with similar results, scientists may wait until an investigation has been repeated many times before accepting the results as meaningful. b. When new experimental results are inconsistent with an existing, well-established theory, scientists may pursue further experimentation to determine whether the results are flawed or the theory requires modification. c. As prevailing theories are challenged by new information, scientific knowledge may change. S8CS9. Students will understand the features of the process of scientific inquiry. Students will apply the following to inquiry learning practices: a. Investigations are conducted for different reasons, which include exploring new phenomena, confirming previous results, testing how well a theory predicts, and comparing different theories. Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses, and formulating explanations to make sense of collected evidence. b. Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses, and formulating explanations to make sense of collected evidence. June 2008 Page 2 of 8

3 c. Scientific experiments investigate the effect of one variable on another. All other variables are kept constant. d. Scientists often collaborate to design research. To prevent this bias, scientists conduct independent studies of the same questions. e. Accurate record keeping, data sharing, and replication of results are essential for maintaining an investigator s credibility with other scientists and society. f. Scientists use technology and mathematics to enhance the process of scientific inquiry. g. The ethics of science require that special care must be taken and used for human subjects and animals in scientific research. Scientists must adhere to the appropriate rules and guidelines when conducting research. Enduring Understanding: Part I: 1. Classifying matter is important because we are able to predict behavior and properties based on the material s characteristics. For example, we know that we can separate sugar from water in a sugar solution because it is a mixture of two compounds. We cannot, however, separate the hydrogen from the oxygen in water without breaking strong chemical bonds within the water molecule. 2. The main difference between physical and chemical changes is what types of bonds you are breaking or forming during the process. Bonds WITHIN a substance requires chemical changes, because new substances are formed. Bonds BETWEEN substances are formed and broken during physical changes; no new substances are formed in these processes. 3. On the macroscopic (what you can see with your eyes) level, it is often difficult to distinguish between these processes based on visual observation alone. At this developmental level (8-9 th grade), students should be encouraged to make claims about these differences based on evidence they collect before, during, and after the process. Classic evidences for chemical changes include the formation of a gas, solid; color change; change in temperature; or emission of light. Unfortunately, many physical changes are also accompanied by these characteristics. 4. The knowledge of basic vocabulary in science allows people to communicate about ideas using a common language. It s easier to carry on a conversation with someone about science when you know some of the basic terminology. June 2008 Page 3 of 8

4 Part II: 1. Models are helpful to visualize a phenomenon that cannot be directly observed or is very complex and thus difficult to understand. 2. Chemical equations are just ways of representing what is happening on the molecular (submicroscopic) level. 3. When atoms rearrange themselves to make new substances, energy is often released or absorbed. However, the total amount of energy before and after the change is always the same. 4. When energy is absorbed by the system, the atoms gain kinetic energy, potential energy, or both. When energy leaves the system, the atoms lose kinetic energy, potential energy, or both. 5. Every spontaneous process occurs in the direction of decreasing (lowering) the energy of the system. Essential Questions: How are chemical and physical changes alike and different? June 2008 Page 4 of 8

5 ADMINISTRATION PROCEDURES Outcome / Performance Expectations: Part I: Correctly assign which of the following concepts a. Atoms b. Element c. Compound d. Mixture e. Solution f. Chemical change g. Physical change apply to the following common materials: Part II: a. A cup of water b. A cup of sugar water c. A cup of sweet tea 1. Ask the students to make a molecule of methane (CH 4 ) and two oxygen molecules (O 2 ). Put the molecules in a cup and weigh them. 2. Tell the students that methane and oxygen can react to form water and carbon dioxide. Ask the students to make the products, draw a picture of the process before and after, and predict the mass of the contents after the reaction. 3. Ask the students to try to use all of these terms in a paragraph about what they just did: a. Chemical/physical change b. Element c. Atom d. Mixture e. Compound f. Reactants/Products g. Evidence for Chemical Change h. Evidence for Physical Change i. Conservation of Matter June 2008 Page 5 of 8

6 General Teacher Instructions: Part I: 1. Distribute a model kit to each group and ask them to make a pile of carbon atoms (black) and sulfur atoms (red). a. Direct the students to take 4 atoms of each element, place them in a separate cup, and draw a picture of this. Label this Scenario 1. b. Combine the contents of the two cups, shake, and draw a picture of this. Label this Scenario 2. Write a brief description of the contents. c. Now try to make a new substance in the cup by using the bonds in the kit to connect the atoms. For a new compound to be considered able to form, all of the holes in the model must have a bond in it. Label this Scenario 3. d. Draw a picture of the contents after all new compounds have been made; write a brief description, too. e. Compare and contrast the cup before and after the bonds were formed. How are they the same? Different? Write at least 3 complete sentences. 2. Ask the students to label each scenario as containing as many of the following as is appropriate, and justify their responses: a. Atoms b. Element c. Compound d. Mixture e. Solution f. Chemical change g. Physical change 3. Discuss the groups responses, ask other groups to respond, then clarify any misconceptions with ideas such as the following: a. Scenario 1: atoms and elements only. Each cup contains identical atoms b. Scenario 2: atoms, elements, mixture, physical change. Atoms of each element still exist; atoms are now physically mixed but are easily separated. No new chemical species have been created. c. Scenario 3: atoms, element, compound, mixture, chemical change, physical change. Atoms of carbon remain; a new compound formed (carbon disulfide); still a mixture of carbon and carbon disulfide; chemical change occurred when carbon disulfide forms; physical change occurs when compound mixes with element. June 2008 Page 6 of 8

7 Part II: 1. Pass out 2 hydrogen atoms and 2 oxygen atoms to each group. Ask the students to construct a molecule of each element (H 2 and O 2 ). Ask them to write the chemical equation for these reactions without any direct instruction. Ask for their responses, then guide them to this conception: a. H + H => H 2 ; O + O => O 2 2. Ask the students to place one molecule of each substance in a cup and ask if the contents are an element, compound, or mixture. Then ask the students to try to make water from the mixture. (To do so, they will have to pull apart (break) bonds within the molecules.) 3. Ask the students to draw a picture of what they started with and what they ended with, and to write about whether that change is best described as a physical or chemical change. 4. Ask the students comment on whether the contents of the cup increased, decreased, or remained the same mass during the process. 5. Ask the students to write an equation for the process they just observed. Guide them to the following: a. H 2 + O 2 => H 2 O + O 6. Help the students note the following: a. Equations can represent what s happening on a molecular level by using symbols for the substances involved. b. Since bonds WITHIN the molecules had to be broken to form water (the new substance), a chemical change occurred. c. The number and types of atoms of each element are the same before and after the process. d. Since the number and types of atoms are the same, so should the mass. The contents of the cup should weigh the same before and after the process. Materials Needed: Molecular Model Kits (available online at Flinn Scientific and others) Pocket Scales (available online at and others) Safety Precautions: Do not swallow the model kit pieces, they are potential choking hazards June 2008 Page 7 of 8

8 Task with Student Directions: See above Resources: Differentiation: ELL s: Less emphasis on the writing, more emphasis on drawing/labeling the scenarios. Gifted: Challenge the students to calculate the amount of energy released or absorbed during the chemical changes using a table of bond dissociation energies. (e.g. Homework / Extension: 1. Construct a molecule of glucose (find the structure on the internet or reference book) and determine how many molecules of oxygen would be needed to completely react with it during cellular respiration. 2. Explain how the model kits accurately represent how molecules behave during chemical and physical processes. 3. Explain what shortcomings the model kits have in explaining the atomic world accurately. June 2008 Page 8 of 8