A Framework for K-12 Science Education Practices, Crosscutting Concepts, and Core Ideas (2012) / Chapter Skim
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5 Dimension 3: Disciplinary Core Ideas - Physical Sciences
5 Dimension 3: Disciplinary Core Ideas - Physical Sciences
Pages 103-138
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From page 103... ...
An overarching goal for learning in the physical sciences, therefore, is to help students see that there are mechanisms of cause and effect in all systems and processes that can be understood through a common set of physical and chemical principles. The committee developed four core ideas in the physical sciences -- three of which parallel those identified in previous documents, including the National Science Education Standards and Benchmarks for Science Literacy [1, 2]
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From page 104... ...
The historical division between the two subjects of physics and chemistry is transcended in modern science, as the same physical principles are seen to apply from subatomic scales to the scale of the universe itself. For this reason we have chosen to present the two subjects together, thereby ensuring a more coherent approach to the core ideas across all grades.
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From page 105... ...
BOX 5-1 CORE AND COMPONENT IDEAS IN THE PHYSICAL SCIENCES Core Idea PS1: Matter and Its Interactions PS1.A: Structure and Properties of Matter PS1.B: Chemical Reactions PS1.C: Nuclear Processes Core Idea PS2: Motion and Stability: Forces and Interactions PS2.A: Forces and Motion PS2.B: Types of Interactions PS2.C: Stability and Instability in Physical Systems Core Idea PS3: Energy PS3.A: Definitions of Energy PS3.B: Conservation of Energy and Energy Transfer PS3.C: Relationship Between Energy and Forces PS3.D: Energy in Chemical Processes and Everyday Life Core Idea PS4: Waves and Their Applications in Technologies for Information Transfer PS4.A: Wave Properties PS4.B: Electromagnetic Radiation PS4.C: Information Technologies and Instrumentation 105 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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From page 106... ...
Chemical reactions, which underlie so many observed phenomena in living and nonliv ing systems alike, conserve the number of atoms of each type but change their arrangement into molecules. Nuclear reactions involve changes in the types of atomic nuclei present and are key to the energy release from the sun and the bal ance of isotopes in matter.
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107 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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From page 108... ...
can be used to identify particular materi als. (Boundary: At this grade level, mass and weight are not distinguished, and no attempt is made to define the unseen particles or explain the atomic-scale mechanism of evaporation and condensation.)
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Changes in matter in which the molecules do not change, but their positions and their motion relative to each other do change also occur (e.g., the forming of a solution, ❚ Understanding chemical reactions and the properties of elements is essential not only to the physical sciences but also is foundational ❚ knowledge for the life sciences and the earth and space sciences. 109 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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From page 110... ...
Any chemical process involves a change in chemical bonds and the related bond energies and thus in the total chemical binding energy. This change is matched by a difference between the total kinetic energy of the set of reactant molecules before the collision and that of the set of product molecules after the collision (conservation of energy)
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From page 111... ...
Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in total binding energy (i.e., the sum of all bond energies in the set of molecules) that are matched by changes in kinetic energy.
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Nuclear fission and radioactive decays limit the set of stable isotopes of ele ments and the size of the largest stable nucleus. Spontaneous radioactive decays follow a characteristic exponential decay law, with a specific lifetime (time scale)
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Strong and weak nuclear interactions determine nuclear stability and processes. Spontaneous radioactive decays follow a characteristic exponential decay law.
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Sometimes forces on an object can also change its shape or orienta tion. For any pair of interacting objects, the force exerted by the first object on the second object is equal in strength to the force that the second object exerts on the first but in the opposite direction (Newton's third law)
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Forces on an object can also change its shape or orientation. All positions of objects and the directions of forces and motions must be described in an arbitrarily chosen reference frame 115 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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By the end of grade 12. Newton's second law accurately predicts changes in the motion of macroscopic objects, but it requires revision for subatomic scales or for speeds close to the speed of light.
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The forces' magnitudes depend on the magnitudes of the charges, currents, and magnetic strengths as well as on the distances between the interacting objects. All objects with electrical charge or magnetization are sources of electric or magnetic fields and can be affected by the electric or magnetic fields of other such objects.
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From page 118... ...
Magnets or changing electric fields cause magnetic fields; electric charges or changing magnetic fields cause electric fields. Attraction and repulsion between electric charges at the atomic scale explain the structure, properties, and transformations of matter, as well as the contact forces between material objects.
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. 119 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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That there is a single quantity called energy is due to the remarkable fact that a system's total energy is conserved. Regardless of the quantities of energy transferred A Framework for K-12 Science Education 120
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When a particle in a molecule of solid matter vibrates, energy is continually being transformed back and forth between the energy of motion and the energy stored in the electric and magnetic fields within the matter. Matter in a stable form minimizes the stored energy in the electric and magnetic fields within it; this defines the equilibrium positions and spacing of the atomic nuclei in a molecule or an extended solid and the form of their combined electron charge distributions (e.g., chemical bonds, metals)
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From page 122... ...
The idea that there are different forms of energy, such as thermal energy, mechanical energy, and chemical energy, is misleading, as it implies that the nature of the energy in each of these manifestations is distinct when in fact they all are ultimately, at the atomic scale, some mixture of kinetic energy, stored ener gy, and radiation. It is likewise misleading to call sound or light a form of energy; they are phenomena that, among their other properties, transfer energy from place to place and between objects.
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"Mechanical energy" generally refers to some combination of motion and stored energy in an operating machine. "Chemical energy" generally is used to mean the energy that can be released or stored in chemical processes, and "electrical energy" may mean energy stored in a battery or energy transmitted by electric currents.
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From page 124... ...
also transfers some of the energy to the sur rounding air by sound or heat. For molecules, collisions can also result in energy transfers through chemical processes, which increase or decrease the total amount of stored energy within a system of atoms; the change in stored energy is always balanced by a change in total kinetic energy -- that of the molecules present after the process compared with the kinetic energy of the molecules present before it.
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Similarly, to make an object start moving or to keep it moving when friction forces transfer energy away from it, 125 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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Mathematical expressions, which quantify how the stored energy in a sys tem depends on its configuration (e.g., relative positions of charged particles, com pression of a spring) and how kinetic energy depends on mass and speed, allow the concept of conservation of energy to be used to predict and describe system behavior.
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When two objects interacting through a force field change relative position, the energy stored in the force field is changed. Each force between the two interacting objects acts in the direction such that motion in that direction would reduce the energy in the force field between the objects.
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From page 128... ...
Therefore, to produce energy typically means to convert some stored energy into a desired form -- for example, the stored energy of water behind a dam is released as the water flows downhill and drives a turbine generator to produce electricity, which is then delivered to users through distribution systems. Food, fuel, and batteries are especially conve nient energy resources because they can be moved from place to place to provide processes that release energy where needed.
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, most often the energy is transferred to heat the surrounding environment. The energy released by burning fuel or digesting food was once energy from the sun that was captured by plants in the chemical process that forms plant matter (from air and water)
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By understanding wave properties and the interactions of electromagnetic radia tion with matter, scientists and engineers can design systems for transferring infor mation across long distances, storing information, and investigating nature on many scales -- some of them far beyond direct human perception. A Framework for K-12 Science Education 130
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When a wave passes an object that is small compared with its wavelength, the wave is not much affected; for this reason, some things are too small to see with visible light, which is a wave phenomenon with a limited range of wavelengths 131 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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A simple wave has a repeating pattern with a specific wavelength, frequency, and amplitude. A sound wave needs a medium through which it is transmitted.
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Electromagnetic ❚ By understanding wave properties and the interactions of electromagnetic radiation with matter, scientists and engineers can design systems for transferring information across long distances, storing information, and investigating nature on many scales -- some of them far ❚ beyond direct human perception. 133 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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Nuclear transitions that emit or absorb gamma radiation also have dis tinctive gamma ray wavelengths, a phenomenon that can be used to identify and trace specific radioactive isotopes. Grade Band Endpoints for PS4.B By the end of grade 2.
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can be modeled as a wave of changing electric and magnetic fields or as particles called photons. The wave model is useful for explaining many features of electromagnetic radiation, and the particle model explains other features.
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Its speed in any other given medium depends on its wave length and the properties of that medium. When light or longer wavelength electromagnetic radiation is absorbed in matter, it is generally converted into thermal energy (heat)
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137 Dimension 3: Disciplinary Core Ideas -- Physical Sciences
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From page 138... ...
National Committee for Science Education Standards and Assessment. Washington, DC: National Academy Press.
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