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New Ohio Physical Science Syllabus and Model Curriculum

Study of Matter     Energy and Waves    Forces and Motion    The Universe

(Edited New Draft from: http://www.ode.state.oh.us/GD/Templates/Pages/ODE/ODEDetail.aspx?page=3&TopicRelationID=1705&ContentID=76585&Content=103133)

Course Description:
Physical Science is a high school introductory-level course which satisfies Ohio Core requirements (ODE, 2008), as required by section 3313.603 of the Ohio Revised Code (ORC). It introduces students to key concepts and theories that provide a foundation for further study in other sciences and advanced science disciplines. Physical Science comprises the systematic study of the physical world as it relates to fundamental concepts about matter, energy, and motion. A unified understanding of phenomena in physical, living, Earth and space systems is the culmination of all previously learned concepts related to chemistry, physics and Earth and space science, along with historical perspective and mathematical reasoning.

The following information may be taught in any order. The sequence provided here does not represent the ODE-recommended sequence as there is no ODE-recommended sequence. Pacing and sequence are to be determined at the local level.

Science Inquiry and Application
During the years of grades 9 through 12 all students must use the following scientific processes with appropriate laboratory safety techniques to construct their knowledge and understanding in all science content areas:

Study of Matter
Course Content

1. Classification of Matter

2. Atoms

3. Periodic Trends of the Elements

4. Bonding and Compounds

5. Reactions of Matter

Energy and Waves
Course Content

1. Conservation of Energy

2. Transfer and Transformation of Energy (including work)

3. Waves

Energy transfer

Refraction, Reflection, Diffraction, Absorption, Superposition

Doppler shift

Forces and Motion
Course Content

1. Motion

2. Forces

3. Dynamics (how forces affect motion) Objects at rest

The Universe
Course Content

1. History of the Universe

2. Galaxy formation

3. Stars

4. Earth and the Solar System

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Study of Matter
Course Content

1. Classification of Matter

2. Atoms

3. Periodic Trends of the Elements

4. Bonding and Compounds

5. Reactions of Matter

Content Elaboration

1. Classification of Matter
Building upon observation, exploration and analytical skills developed at the elementary and middle school levels more extensive knowledge about matter, its composition and the changes its basic particles undergo under various conditions is further constructed. Specific content from middle school, including the particulate nature of matter, elements, compounds, molecules, and kinetic and potential energy, provides the foundational knowledge necessary to understand the concepts in this section. The content at this grade level provides the foundation for topics that will be studied later. For example, concepts in chemistry like electron configuration, molecular shapes and bond angles will use explanations derived from understanding the phenomena observed in physical science.

Matter can be classified in broad categories such as homogeneous and heterogeneous. It also can be classified according to its composition, such as elements, compounds, and mixtures, or by its chemical and physical properties. Physical properties include color, solubility, odor, hardness, density, melting point and boiling point, viscosity, and malleability. These properties can be used to identify a material, to choose a material for a specific purpose, or to separate the substances in a mixture. The chemical properties, like the reactivity of a substance, can also be studied. These distinctions and categorizations are made to better understand the composition of matter and help predict its behavior under specific conditions.

As studied in middle school, many differences in the physical properties of solids, liquids, and gases are explained by the motion of the particles from which the matter is comprised, and the strength of the attractions between them. Matter can go through a series of phase changes as it is heated or cooled. These changes can be identified by graphing the temperature of a sample versus the time it has been heated. At times, the temperature will change steadily, indicating a change in the motion of the particles and the kinetic energy of the substance. However, during a phase change the temperature of a substance does not change, indicating there is no change in kinetic energy. Since the substance continues to gain or lose energy during phase changes, these changes in energy are potential and indicate a change in the position of the particles. When heating a substance, a phase change will occur when the kinetic energy of the particles is great enough to overcome the attractive forces between the particles; the substance then melts or boils. Conversely, when cooling a substance, a phase change will occur when the kinetic energy of the particles is no longer great enough to overcome the attractive forces between the particles; the substance then condenses or freezes. These changes illustrate some of the changes that can occur when energy is absorbed from the surroundings (endothermic), or released into the environment (exothermic). [Back to Study of Matter Outline]

2. Atoms
The model of the atom has changed significantly over time. The ancient Greeks envisioned the atom as small, indestructible spheres. Over time it was learned that the atom is composed of protons, neutrons and electrons that have measurable properties, including mass and, in the case of protons and electrons, a characteristic charge. More recent models indicate that an atom has a very small nucleus composed of protons and neutrons. Electrons move about in the empty space that surrounds the nucleus and makes up most of the atom. These models expand the concept of the particulate nature of matter previously discussed in middle school. Specific experimental evidence that led to the development of atomic models will be studied in Chemistry.

Atomic structure determines the properties of an element and how an atom (of the element) will interact with other atoms. The number of protons in an atom gives the atom its elemental identity and is called the atomic number. Neutrons have little effect on how an atom interacts with other atoms, but they do affect the mass and stability of the nucleus. Since protons and neutrons comprise nearly all of the mass of an atom, the mass number of an atom is the sum of the protons and neutrons. Atoms of an element whose nuclei have different numbers of neutrons and therefore different masses and mass numbers are called isotopes. Atoms of an element with a different number of protons and electrons have an unbalanced charge and are called ions. Negatively-charged ions are called anions and positively-charged ions are called cations. [Back to Study of Matter Outline]

3. Periodic Trends of the Elements
When elements are listed in order of increasing number of protons, the same sequence of properties appears over and over again; this is the periodic law. At times the masses do not correspond with periodic order, but the atomic number always does. The periodic table is also arranged so that elements with similar chemical and physical properties are in the same column. Horizontal rows are called periods and vertical columns are called groups or families. Specific names are assigned for representative groups (e.g., alkali metals, alkaline earth metals, halogens and noble gases). Certain families have characteristic ionic charges that will be used later to predict the formulas of compounds. Metals and nonmetals were introduced in middle school. Metalloids are elements that have some properties of metals and some properties of nonmetals. Metals, nonmetals, and metalloids can be identified according to their position on the periodic table. Other trends in the periodic table, including atomic radii and electronegativity are discussed in chemistry. [Back to Study of Matter Outline]

4. Bonding and Compounds
Chemical bonding describes how the interactions between atoms hold them together in molecules and three-dimensional lattices. Atoms may be bonded together by losing, gaining or sharing electrons. When two atoms transfer an electron between them, a cation and anion are formed. An ionic bond involves the attraction of these two oppositely charged ions, typically a metal cation and a nonmetal anion. An ion attracts oppositely charged ions from every direction, resulting in the formation of a three-dimensional lattice. Covalent bonds result from the sharing of electrons between two atoms, usually nonmetals. Covalent bonding can result in the formation of structures ranging from small individual molecules to three-dimensional lattices (e.g. diamond). The bonds in most compounds fall on a continuum between the two extreme models of bonding: ionic and covalent. Prediction of bond types from electronegativity values and polar covalent bonds are studied in chemistry.

Using the periodic table, formulas of ionic compounds containing specific elements can be predicted. This can include ionic compounds made up of elements from groups 1, 2, 17, hydrogen and oxygen. Given the formula, a compound can be named using conventional systems that include Greek prefixes and where appropriate. Given the name of an ionic or covalent substance, formulas can be written. Naming organic molecules is beyond this grade level and is reserved for an advanced chemistry course. Writing formulas and naming compounds that contain polyatomic ions or transition metals will be reserved for chemistry. Prefixes will be limited to represent values from one to ten. [Back to Study of Matter Outline]

5. Reactions of Matter
During chemical reactions, energy is either released to the environment (exothermic), or absorbed from the environment (endothermic). As learned in middle school, matter is always conserved in all chemical and non-chemical processes therefore it is never created or destroyed. In a chemical reaction, the number and type of atoms and the total mass are the same before and after the reaction.

Chemical reactions can also be studied by using equations to represent how the arrangement of atoms in the reactants rearranges to form the products. During the reaction, the number and type of atoms remain the same. This conservation of matter is represented by a balanced equation. Given the formulas of the reactants and products, equations can be balanced by adding coefficients, which represent how many units of the substance are involved in the reaction. Balanced equations can also be written from a word description of the reaction. At this level, reactants and products can be identified from an equation and simple equations can be written and balanced. For example, nitrogen gas plus oxygen gas yields nitrogen dioxide gas can be expressed as N2 (g) + 2O2 (g) → 2NO2 (g). More complex stoichiometric relationships and classification of types of chemical reactions and is reserved for chemistry.

While chemical changes involve changes in how the electrons are transferred or shared, nuclear reactions involve changes to the nucleus, and therefore the protons and neutrons. The strong nuclear force is the attractive force that binds protons and neutrons together in the nucleus. Over very short distance(less than 10-15 meters) this force is much greater than the repulsive electrical forces among protons. The nuclear force is extremely weak over greater distances. However, the greater the number of protons in a nucleus, the greater the electrical force that repels those protons. When the attractive and repulsive forces in the nucleus are not balanced, the nucleus is unstable. Through a process called radioactive decay, the unstable nucleus emits radiation in the form of very fast moving particles and energy to produce a new nucleus which may have a different number of protons thus changing the identity of the element. Nuclei that undergo this process are said to be radioactive. These radioisotopes have several medical applications. The radiation they release can be used to kill undesired cells (e.g., cancer cells). Since the radiation they release can be detected, radioisotopes can be introduced into the body and used to show the flow of materials in biological processes.

The time that is required for one half of a sample of radioactive material to decay is known as the half-life of the material. For any radioisotope, this half-life is unique and constant. Graphs can be constructed and interpreted that show amount of a radioisotope that remains as a function of time. Half-life values are used in radioactive dating, a method of calculating the age of a sample by measuring its levels of carbon-14 (comparing the objects’ carbon-14 levels with carbon-14 levels in the atmosphere).

Other examples of nuclear reactions include nuclear fission and nuclear fusion. Nuclear fission involves the decay, or splitting, of large nuclei into smaller nuclei, releasing large quantities of energy. Nuclear fusion is the joining of nuclei into a larger nucleus accompanied by the release of large quantities of energy, much larger than from chemical reactions. Nuclear fusion is the process responsible for the formation of stars, formation of all the elements in the universe beyond helium, and the energy of the Sun. More detailed instruction about fission and fusion processes is outside of the boundary for this grade level and will be addressed in chemistry and physics. Further details about nuclear processes including common types of nuclear radiation, predicting the products of nuclear decay, mass-energy equivalence, and nuclear power applications are reserved for chemistry and physics. [Back to Study of Matter Outline]

Some Instructional Strategies and Resources:
The World of Chemistry is a video instructional series comprising 26 half-hour video programs for college and high school classrooms and adult learners produced by the University of Maryland and the Educational Film Center with Annenberg Media ©. Titles include: Measurement: The Foundation of Chemistry; Modeling the Unseen; A Matter of State; The Atom; The Periodic Table; Chemical Bonds; Metals; Futures

Some Common Misconceptions
Students may think that models are physical copies of the real thing, failing to recognize models as conceptual representations. (AAAS, 1993)

Students know models can be changed, but at the high school level they may be limited by thinking that a change in a model means adding new information, or that changing a model means replacing a part that was wrong. (AAAS, 1993)

Students often do not believe models can duplicate reality. (AAAS, 1993)

When multiple models are presented, they tend to think there is one “right one”. (AAAS, 1993)

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Energy and Waves
Course Content

1. Conservation of Energy

2. Transfer and Transformation of Energy (including work)

3. Waves

Energy transfer

Refraction, Reflection, Diffraction, Absorption, Superposition

Doppler shift

 

Content Elaboration

Energy and Waves
Building upon knowledge gained in elementary and middle school, major ideas about energy and waves are further developed. Conceptual knowledge will move from qualitative understandings of energy and waves to ones that are more quantitative using mathematical formulas, manipulations and graphical representations.

1. Conservation of Energy
Energy is a scalar quantity and has units of Joules (J). As learned in middle school, energy is always conserved. For closed systems in which no energy is transferred into or out of the system, the total initial energy of the system is equal to the total final energy of the system. In middle school the concepts of kinetic and potential energy were introduced. In physical science kinetic energy and gravitational potential energy are quantified and used to calculate values associated with energy (i.e., height, mass, speed). Kinetic energy, Ek, can be mathematically represented by Ek=½mv 2, where m and v are the mass and speed of the object. Gravitational potential energy, Eg, can be mathematically represented by Eg=mgh, where g=9.8 m/s 2, and m and h are the mass and height of the object above a reference point. The amount of energy of an object is measured relative to a reference that is considered to be at a point of zero energy. The reference may be changed to help understand different situations. Only the change in the amount of energy can be measured absolutely. [Back to Energy and Waves outline]

2. Transfer and Transformation of Energy
In middle school, the concepts of energy transfer and transformation are introduced, including conservation of energy, conduction, convection, and radiation, the transformation of electrical energy, and the dissipation of energy into heat. When an outside force moves an object over a distance, energy has been transferred either into or out of the system. As learned in middle school, this method of energy transfer is called work. As long as the force, F, and displacement, Δx, are in the same direction, work, W, can be calculated from the equation W=FΔx. Energy transformations for a phenomenon can be represented through a series of pie graphs or bar graphs. Equations for work, kinetic energy, and potential energy can be combined with the law of conservation of energy to solve problems. [Back to Energy and Waves outline]

3. Waves
As learned in middle school, waves transmit energy from one place to another, can transfer energy between objects, obey the law of conservation of energy, and can be described by their speed, wavelength, frequency, and amplitude. A wave travels at a constant speed through a particular material, as long as it is uniform (e.g. for water waves, having the same depth). The speed of the wave (vwave) depends on the nature of the material (e.g., waves travel faster through solids than gases). For a particular uniform medium, as the frequency (f) of the wave is increased, the wavelength (λ) of the wave is decreased. The mathematical representation is vwave=λf. [Back to Energy and Waves outline]

When a wave encounters a new material, the new material may absorb the energy of the wave by transforming it to another form of energy, usually thermal energy. This interaction is called absorption. Waves can bounce off solid barriers. This interaction is called reflection. When a wave travels form one material (medium) into another material, its direction may change. This interaction is called refraction. Waves may bend around small obstacles or openings. This interaction is called diffraction. When two waves traveling through the same medium meet, they pass through each other then continue traveling through the medium as before. When the waves meet and occupy the same part of the medium, the displacement of the two waves adds algebraically. This interaction is called superposition. In physics, many of these wave phenomena will be studied further and quantified. [Back to Energy and Waves outline]

The wavelength and observed frequency of a wave depends upon the relative motion of the source and the observer. If either is moving toward the other, the wavelength is shorter and the observed frequency is higher; if either is moving away, the wavelength is longer and the observed frequency is lower. This phenomenon is called the Doppler shift and can be explained using diagrams. Calculations to measure the apparent change in frequency or wavelength are not appropriate at this grade level. [Back to Energy and Waves outline]

Some Instructional Strategies and Resources: This section provides additional support and information for educators. These are strategies for actively engaging students with the topic and for providing hands-on minds-on observation and exploration of the topic, including authentic data resources for scientific inquiry, experimentation and problem-based tasks that incorporate technology and technological and engineering design. Resources selected are printed or web-based materials that directly relate to the particular Content Statement. It is not intended to be a prescriptive list of lessons.

" Energy: Misconceptions and Models" is a downloadable document from the U.K. Department for Education that gives strategies for teaching different models of energy and addressing misconceptions about energy.

" Waves, Light, and Sound" from The Physics Zone, links to many animations of waves that can be used with absent students or students who need more reinforcement. Simulations may also be good to slow down some of the phenomena that students observe in class, so they can make more detailed observations. Some of the simulations can only be accessed by members, but many of the simulations have unrestricted access.

Modeling workshops are available nationally that help teachers develop a framework for using guided inquiry in their instruction.

Some Common Misconceptions
Students often think that: Potential energy is a thing that objects hold (like cereal stored in a closet). The only type of potential energy is gravitational. Doubling the velocity of a moving object will double its kinetic energy. Stored energy is something that causes energy later; it is not energy until it has been released. Objects do not have any energy if they are not moving. Energy is a thing that can be created and destroyed. Energy is literally lost in many energy transformations. Gravitational potential energy depends only upon the height of an object. Energy can be changed completely from one form to another with no loss of useful energy.

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Forces and Motion
Course Content

1. Motion

2. Forces

3. Dynamics (how forces affect motion) Objects at rest

Content Elaboration
Forces and Motion

Building upon knowledge gained in elementary and middle school, major ideas of motion and forces are further developed. In middle school, speed has been dealt with conceptually, mathematically and graphically. The ideas that forces have both magnitude and direction, can be represented with a force diagram, can be added to find a net force, and may affect motion have also been discussed. In physical science mathematics, including graphing is used when describing these phenomena, moving from qualitative understanding to one that is more quantitative. At this level, all motion is limited to objects moving in a straight line either horizontally, vertically, up an incline, or down an incline, that can be characterized in a single step (e.g., at rest, constant velocity, constant acceleration). Motions of two objects may be compared or addressed simultaneously (e.g., when or where would they meet).

1. Motion
The motion of an object depends on the observer’s frame of reference and is described in terms of distance, position, displacement, speed, velocity, acceleration and time. Position, displacement, velocity, and acceleration are all vector properties because they have both magnitude and direction. All motion is relative to whatever frame of reference is chosen, for there is no motionless frame from which to judge all motion. The relative nature of motion will be addressed conceptually, not mathematically, and only inertial frames of reference will be used. Motion diagrams can be drawn and interpreted to represent the position and velocity of an object. Showing the acceleration on motion diagrams will be reserved for physics. [Back to Outline]

The displacement, or change in position of an object is a vector quantity that can be calculated by subtracting the initial position from the final position (Δx = xf – xi). Displacement can be positive or negative depending upon the direction of motion. Displacement is not always equal to the distance traveled. Examples should be given where the distance is not the same as the displacement. [Back to Outline]

Velocity is a vector property that represents the rate at which position changes. Average velocity can be calculated by dividing displacement (change in position) by the elapsed time (vavg = (xf – xi)/(tf – ti)). Velocity may be positive or negative depending upon the direction of motion and is not always equal to the speed. Examples should be given the average speed is not the same as the average velocity. Objects that move with constant velocity have the same displacement for each successive time interval. While speeding up or slowing down and/or changing direction, the velocity of an object changes continuously, from instant to instant. The velocity of an object at any instant (clock reading) is called instantaneous velocity. An object may not travel at this instantaneous velocity for any period of time or cover any distance with that particular velocity, especially if the velocity is continually changing. [Back to Outline]

Acceleration is a vector property that represents the rate at which velocity changes. Average acceleration can be calculated by dividing the change in velocity divided by elapsed time (aavg = (vf – vi)/(tf – ti)). At this grade level, it should be noted that acceleration can be positive or negative, but specifics about what kind of motions produce positive or negative accelerations will be reserved for physics. The word “deceleration” should not be used because students tend to associate a negative sign of acceleration only with slowing down. Objects that have no acceleration can either be standing still or be moving with constant velocity (speed and direction). Constant acceleration occurs when the change in an object’s instantaneous velocity is the same for equal successive time intervals. [Back to Outline]

Motion can be represented by position vs. time and velocity vs. time graphs. Specifics about the speed, direction, and change in motion can be determined by interpreting such graphs. For physical science, graphs will be excluded to positive x-values and show only uniform motion involving constant velocity or constant acceleration.

Objects that move with constant velocity and have no acceleration form a straight line (not necessarily horizontal) on a position vs. time graph. Objects that are at rest will form a straight horizontal line on a position vs. time graph. Objects that are accelerating will show a curved line on a position vs. time graph. Velocity can be calculated by determining the slope of a position vs. time graph. Positive slopes on position vs. time graphs indicate motion in a positive direction. Negative slopes on position vs. time graphs indicate motion in a negative direction.

Constant acceleration is represented by a straight line (not necessarily horizontal) on a velocity vs. time graph. Objects that have no acceleration (at rest or moving at constant velocity) will have a straight horizontal line for a velocity vs. time graph. Average acceleration can be by determining the slope of a velocity vs. time graph. The details about motion graphs should not be taught as rules to memorize, but rather as generalizations that can be developed from interpreting the graphs. [Back to Outline]

2. Forces
Forces are used to understand motion through Newton’s Laws. Force is a vector quantity, having both magnitude and direction. The (SI) unit of force is a Newton. One Newton of net force will cause a 1 kg object to experience an acceleration of 1 m/s2. A Newton can also be represented as kg•m/s2. Friction and normal forces are introduced conceptually at this level. These forces and other forces discussed in prior grades (contact, gravitational, electric and magnetic) can be used as examples of forces that affect motion. Gravitational force (weight) can be calculated from mass, but all other forces will only be quantified from force diagrams that were introduced in middle school. In physical science, only forces in one-dimension (positive and negative) will be addressed. The net force can be determined by one-dimensional vector addition. More quantitative study of friction forces, universal gravitational forces, elastic forces, and electrical forces will occur in physics. [Back to Outline]

Friction is a force that opposes sliding between two surfaces. For surfaces that are sliding relative to each other, the force on an object always points in a direction opposite to the relative motion of the object. In nearly all commonly experienced situations, friction complicates the understanding of motion, although the basic principles still apply when friction is considered. In physical science, friction will only be calculated from force diagrams. Equations for static and kinetic friction will be discussed in physics. [Back to Outline]

A normal force exists between two solid objects when their surfaces are pressed together due to other forces acting on one or both objects (e.g., a solid sitting on or sliding across a table, a magnet attached to a refrigerator). A normal force is always a push directed at right angles from the surface of the interacting objects. A tension force occurs when a non-slack rope, wire, cord, or similar device pulls on another object. The tension force always points in the direction the device is pulling. [Back to Outline]

Gravitational, magnetic, and electrical forces occur even when objects are not touching. No substance is required between the interacting objects; these are called forces at a distance. The field model is used to represent forces at a distance and is described by regions of influence called fields that surround objects. When an object with the appropriate property (mass for gravitational fields, charge for electric fields, a magnetic object for magnetic fields) enters the field, the field exerts a force on it (e.g., a magnet moving a compass needle). The stronger the field, the greater the force exerted on objects placed in the field. The field of an object is always there, even if the object is not interacting with anything else. The gravitational force (weight) of an object is proportional to its mass. For objects near Earth’s surface weight, Fg, can be calculated from the equation Fg = m g where g=9.8 m/s 2. [Back to Outline]

3. Dynamics
An object does not accelerate (remains at rest or maintains a constant speed and direction of motion) unless an unbalanced net force acts on it. The rate at which an object changes its speed or direction (acceleration) is proportional to the vector sum of the applied forces (net force) and inversely proportional to the mass (a = Fnet/m). When the vector sum of the forces (net force) acting on an object is zero, the object does not accelerate. For an object that is moving, this means the object will remain moving without changing its speed or direction. For an object that is not moving, the object will continue to remain stationary. These laws will be applied to systems consisting of a single object upon which multiple forces act. Vector addition will be limited to one-dimension. While both horizontal and vertical forces can be acting on an object simultaneously, one of the dimensions must have a net force of zero. In physics, Newton's third law will be introduced and all laws will be applied to systems of many objects. [Back to Outline]

Some Instructional Strategies and Resources: This section provides additional support and information for educators. These are strategies for actively engaging students with the topic and for providing hands-on minds-on observation and exploration of the topic, including authentic data resources for scientific inquiry, experimentation and problem-based tasks that incorporate technology and technological and engineering design. Resources selected are printed or web-based materials that directly relate to the particular Content Statement. It is not intended to be a prescriptive list of lessons.

" Forces in 1-dimension" is an interactive simulation that allows students to explore the forces at work when trying to push a filing cabinet. An applied force is created and the resulting friction force and total force acting on the cabinet are then shown. Forces vs. time, position vs. time, velocity vs. time, and acceleration vs. time graphs can be shown as can force diagrams representing all the forces (including gravitational and normal forces).

" Motion Diagrams" is a tutorial from Western Kentucky University that shows how to draw motion diagrams for a variety of motions. It includes an animated physlet. Motion diagrams in physical science will only show position and velocity and will not show acceleration.

The Physics Classroom supports this tutorial on one-dimensional motion that gives a thorough explanation of acceleration, including an animation to use with students who may still be having difficulties with acceleration.

Modeling workshops are available nationally that help teachers develop a framework for incorporating guided inquiry in their instruction.

Some Common Misconceptions
Students often think that: If the speed is constant then there is no acceleration. Students think that high velocities coincide with large accelerations and low velocities coincide with small accelerations.

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The Universe
Course Content

1. History of the Universe

2. Galaxy formation

3. Stars

4. Earth and the Solar System

Content Elaboration

The Universe
Building a unified understanding of the universe from elementary and middle school science, insights from history, and mathematical ways of thinking, provides a basis for knowing the nature of the universe. Concepts from the previous section, Forces, Motion and Energy, are also used as foundational knowledge. The role of gravity in forming and maintaining the organization of the universe becomes clearer at this level, as well as the scale of billions and speed of light used to express relative distances. Instructional content includes:

1. History of the Universe
The origin of the universe remains one the greatest questions in science. Mathematical models and computer simulations are used in studying evidence from many sources in order to form a scientific account of the universe. Astronomers theorize that the universe came into being at a single moment, in an event called the big bang. The big bang theory places the origin of the universe at approximately 13.7 billion years ago when the universe began as a hot, dense, chaotic mass. According to this theory, the universe has been expanding ever since. After the big bang, the universe expanded quickly and then cooled down enough for atoms to form. Gravity pulled the atoms together into gas clouds that eventually evolved into stars, which comprise young galaxies.

When physicists noticed a signal on their radio telescope they eventually realized that they were detecting a faint distant glow in every direction. This led to the discovery of the cosmic microwave background radiation, radiation from the original big bang that is still traveling through the universe. This radiation is evidence that supports the big bang theory thereby explaining the expansion of the observable universe.

Increasingly sophisticated technology is used to learn about the universe. Visual, radio, and x-ray telescopes collect information from across the entire electromagnetic spectrum; computers handle data and complicated computations to interpret them; space probes send back data and materials from remote parts of the solar system; and accelerators provide subatomic particles energies that simulate conditions in the stars and in the early history of the universe before stars formed. [Back to Earth and the Universe Outline]

2. Galaxy Formation
A galaxy is a huge group of individual stars, star systems, star clusters, dust, and gas bound together by gravity. There are billions of galaxies in the universe, and they vary in size and shape. There are three main types, as classified by astronomers, disk (spiral and barred-spiral), elliptical, and irregular. The Milky Way, a spiral galaxy, is the name of our galaxy. It has more than 100 billion stars and a diameter of more than 100,000 light years. At the center of our galaxy is a bulge of stars, from which are spiral arms of gas, dust, and most of the young stars. The entire galaxy is also surrounded by an enormous halo of globular clusters.

Looking at other galaxies, astronomers are able to measure their motion using red shift. Hubble’s Law is that galaxies that are farther away have a greater red shift, thus, the speed at which a galaxy is moving away is proportional to its distance from us. Red shift is a phenomenon due to Doppler shifting, so the shift of light from a galaxy to the red end of the spectrum indicates that the galaxy and the observer are moving farther away from one another. Thus, as previously stated, all of this supports the big bang theory. [Back to Earth and the Universe Outline]

3. Stars
The process of star formation and evolution continues in a cycle of matter in the universe that is very efficient. Stars form by condensing due to gravity out of clouds of molecules of the lightest elements. As the clouds collapse, the density and temperature in the core of the newly forming star increase until nuclear fusion of the light elements into heavier ones can occur. All of the naturally occurring elements, with the exception of hydrogen and helium, originated from the nuclear fusion reactions in stars. Fusion releases great amounts of energy. Because of the amounts of light elements in the cores of stars, these reactions can continue to occur for millions or billions of years. Eventually, the most massive stars explode, producing clouds containing heavy elements from which other stars could later condense. Unlike the sun, most stars are in systems of two or more stars orbiting around one another.

Stars like the Sun, transform matter into energy in nuclear reactions in their cores. When hydrogen nuclei fuse to form helium, a small amount of matter is converted to energy. This production of heavier elements from lighter elements by stellar fusion has never ceased and continues today. These and other fusion processes in stars have led to the formation of all the other elements.

Stars are classified by their color, size, brightness and mass. Astronomers use a Hertzprung-Russell diagram to estimate the sizes of stars and predict how stars will change over time. The H-R diagram is a graph of the surface temperature, or color, and absolute brightness of a sample of stars. Astronomers have found that most stars fall on the main sequence of the H-R diagram, a diagonal band running from the bright hot stars on the upper left to the dim cool stars on the lower right. A star’s mass determines the star’s place on the main sequence and how long it will stay there. Also, in accordance with the H-R diagram, the size and surface temperature can be estimated thereby identifying the stage of evolution for the star (protostar, main sequence, red giant, white dwarf, black dwarf, and supergiant). For low-mass stars, the evolutionary sequence is:

protostar, main sequence, red giant, planetary nebula, white dwarf, black dwarf. For high-mass stars, the evolutionary sequence is: protostar, main sequence, red giant, supergiant, supernova, neutron star (but for the most massive stars, the end stage is black hole). [Back to Earth and the Universe Outline]

4. Earth and the Solar System
Our solar system (including our sun) coalesced out of a giant cloud of gas and debris left in the wake of exploding stars about five billion years ago and is located about 2/3 of the way out from the center of the Milky Way. As Earth and other planets formed, the heavier elements coalesced in their centers. On terrestrial planets closest to the sun (Mercury, Venus, Earth, and Mars) the lightest elements were mostly removed by radiation from the newly formed sun; on the outer planets (Jupiter, Saturn, Uranus and Neptune), the lighter elements still surround them as deep atmospheres of icy, dense gas. Everything in and on Earth, including living organisms, is made of the material from the original cloud.

Earth is part of a solar system and has unique characteristics based on its position. Planetary differentiation is a process in which more dense materials of a planet sink to the center, while less dense materials stay on the surface. A major period of planetary differentiation occurred approximately 4.6 billion years ago. Earth’s position relatively close to the sun, puts it within the habitable zone of a star like our sun. Venus and Mars are also in the habitable zone of our sun. [Back to Earth and the Universe Outline]

Some Instructional Strategies and Resources: This section provides additional support and information for educators. These are strategies for actively engaging students with the topic and for providing hands-on minds-on observation and exploration of the topic, including authentic data resources for scientific inquiry, experimentation and problem-based tasks that incorporate technology and technological and engineering design. Resources selected are printed or web-based materials that directly relate to the particular Content Statement. It is not intended to be a prescriptive list of lessons.

Astronomy: Eliciting Student Ideas is a workshop produced by Annenberg that uses constructivism by examining student beliefs on what causes the seasons and their explanations for the phases of the moon that are explored in the video on demand "A Private Universe".

The Quantum Mechanical Universe is a video produced by Annenberg about a current look at where we've been and a peek into the future.

Dying stars and Birth of Elements is a computer-based exercise where high school students analyze realistically simulated X-ray spectra of a supernova remnant and determine the abundances of various elements in them. In the end, they will find that the elements necessary for life on Earth—the iron in their blood, the calcium in their bones— are created in these distant explosions.

Solar System Activities for the classroom is an aid for building lessons on the topic of the Solar System.

" A Star is Born . . . but How?" and " Stars" are two tutorials on the Windows to the Universe from the National Earth Science Teachers Association that give details about star formation.

Exploring Mars is a video produced by Annenberg that shows students in an 11th-grade integrated science class who explore how the Mars landscape may have formed.

Some Common Misconceptions
Students may believe that the world has always been the way it is now and any changes that occurred were sudden and comprehensive (Freyberg, 1985).

Scale drawings help students understand how the distances to the Moon and the Sun were estimated and why the stars must be very far away (AAAS, 1993, p.63).

Students’ understanding of the magnitude of the universe needs to developed where they have can make sense of how large is a billion or a million. Keely , Eberle & Tugel (2005) suggests teaching the notion of scale with familiar objects that students can see, like the Moon and Sun. Gradually introduce the nearby planets and then planets further away.(p.182)

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