10G/H2 ( Grades: 9-12 ): Ernest Rutherford of New Zealand and his colleagues discovered that the heavy radioactive element uranium spontaneously splits itself into a slightly lighter nucleus and a very light helium nucleus, leading to the realization that one kind of atom may change into another kind, and that therefore an atom must be made up of smaller parts.
10G/H3a ( Grades: 9-12 ): Otto Hahn and Fritz Strassmann, German chemists, found that when they struck uranium with a beam of neutrons, barium was unexpectedly produced. Austrian physicist Lise Meitner, who had earlier worked with Hahn and Strassmann on the decay patterns of uranium, was the first to suggest that the barium could have resulted from the splitting of the uranium nucleus into two middleweight nuclei and one or two extra neutrons.
10G/H3c ( Grades: 9-12 ): Enrico Fermi, an Italian working with colleagues in the United States, showed that the extra neutrons trigger more fissions in uranium nuclei and so create a sustained chain reaction in which a prodigious amount of energy is given off.
10G/H4a ( Grades: 9-12 ): A massive effort went into developing the technology for the production of nuclear fission bombs used against Japan in World War II. The hydrogen bomb, which uses nuclear fusion, was developed shortly after World War II. Another important development of this era was the nuclear reactor, in which nuclear energies are released in a controlled fashion for the production of electrical energy.
10G/H5 ( Grades: 9-12 ): Radioactivity has many uses other than generating energy, including in medicine, industry, and scientific research in many different fields.
10J/M2 ( Grades: 6-8 ): The invention of the steam engine was at the center of the Industrial Revolution. It converted the chemical energy stored in wood and coal into motion energy. The steam engine was widely used to solve the urgent problem of pumping water out of coal mines. As improved by James Watt, Scottish inventor and mechanical engineer, it was soon used to move coal; drive manufacturing machinery; and power locomotives, ships, and even the first automobiles.
11C/H10 ( Grades: 9-12 ): Whatever happens within a system, such as parts exploding, decaying, or reorganizing, some features, such as the total amount of matter and energy, remain precisely the same.
11D/M1 ( Grades: 6-8 ): Some properties of an object depend on its length, some depend on its area, and some depend on its volume.
12B/H1 ( Grades: 9-12 ): Use appropriate ratios and proportions, including constant rates, when needed to make calculations for solving real-world problems.
12C/H3 ( Grades: 9-12 ): Troubleshoot common mechanical and electrical systems, check for possible causes of malfunction, and decide on that basis whether to fix it themselves or get help from an expert.
12C/M3 ( Grades: 6-8 ): Make accurate measurements of length, volume, weight, elapsed time, rates, and temperature by using appropriate devices.
1B/P2 ( Grades: K-2 ): Tools such as thermometers, magnifiers, rulers, or balances often give more information about things than can be obtained by just observing things unaided.
4A/E6 ( Grades: 3-5 ): A large light source at a great distance looks like a small light source that is much closer.
4A/H2cd ( Grades: 9-12 ): Stars condensed by gravity out of clouds of molecules of the lightest elements until nuclear fusion of the light elements into heavier ones began to occur. Fusion released great amounts of energy over millions of years.
4B/E3 ( Grades: 3-5 ): When liquid water disappears, it turns into a gas (vapor) in the air and can reappear as a liquid when cooled, or as a solid if cooled below the freezing point of water. Clouds and fog are made of tiny droplets or frozen crystals of water.
4B/H6 ( Grades: 9-12 ): The earth's climates have changed in the past, are currently changing, and are expected to change in the future, primarily due to changes in the amount of light reaching places on the earth and the composition of the atmosphere. The burning of fossil fuels in the last century has increased the amount of greenhouse gases in the atmosphere, which has contributed to Earth's warming.
4B/H8 ( Grades: 9-12 ): The earth has many natural resources of great importance to human life. Some are readily renewable, some are renewable only at great cost, and some are not renewable at all.
4B/M10ab ( Grades: 6-8 ): Some material resources are very rare and some exist in great quantities. The ability to obtain and process resources depends on where they are located and the form they are in. As resources are depleted, they may become more difficult to obtain.
4B/M11a ( Grades: 6-8 ): The wasteful or unnecessary use of natural resources can limit their availability for other purposes. Restoring depleted soil, forests, or fishing grounds can be difficult and costly.
4B/M11bc ( Grades: 6-8 ): The benefits of Earth's resources—such as fresh water, air, soil, and trees—can be reduced by deliberately or inadvertently polluting them. The atmosphere, the oceans, and the land have a limited capacity to absorb and recycle waste materials. In addition, some materials take a long time to degrade. Therefore, cleaning up polluted air, water, or soil can be difficult and costly.
4B/M9 ( Grades: 6-8 ): Thermal energy carried by ocean currents has a strong influence on climates around the world. Areas near oceans tend to have more moderate temperatures than they would if they were farther inland but at the same latitude because water in the oceans can hold a large amount of thermal energy.
4C/H3 ( Grades: 9-12 ): The outward transfer of the earth's internal heat causes regions of different temperatures and densities. The action of a gravitational force on regions of different densities causes the rise and fall of material between the earth's surface and interior, which is responsible for the movement of plates.
4C/M1 ( Grades: 6-8 ): The interior of the earth is hot. Heat flow and movement of material within the earth cause earthquakes and volcanic eruptions and create mountains and ocean basins. Gas and dust from large volcanoes can change the atmosphere.
4D/E1 ( Grades: 3-5 ): Heating and cooling can cause changes in the properties of materials, but not all materials respond the same way to being heated and cooled.
4D/E6 ( Grades: 3-5 ): All materials have certain physical properties, such as strength, hardness, flexibility, durability, resistance to water and fire, and ease of conducting heat.
4D/H4 ( Grades: 9-12 ): The nucleus of radioactive isotopes is unstable and spontaneously decays, emitting particles and/or wavelike radiation. It cannot be predicted exactly when, if ever, an unstable nucleus will decay, but a large group of identical nuclei decay at a predictable rate. This predictability of decay rate allows radioactivity to be used for estimating the age of materials that contain radioactive substances.
4D/M10 ( Grades: 6-8 ): A substance has characteristic properties such as density, a boiling point, and solubility, all of which are independent of the amount of the substance and can be used to identify it.
4E/H1 ( Grades: 9-12 ): Although the various forms of energy appear very different, each can be measured in a way that makes it possible to keep track of how much of one form is converted into another. Whenever the amount of energy in one place diminishes, the amount in other places or forms increases by the same amount.
4E/H10 ( Grades: 9-12 ): If no energy is transferred into or out of a system, the total energy of all the different forms in the system will not change, no matter what gradual or violent changes actually occur within the system.
4E/H2 ( Grades: 9-12 ): In any system of atoms or molecules, the statistical odds are that the atoms or molecules will end up with less order than they originally had and that the thermal energy will be spread out more evenly. The amount of order in a system may stay the same or increase, but only if the surrounding environment becomes even less ordered. The total amount of order in the universe always tends to decrease.
4E/H3 ( Grades: 9-12 ): As energy spreads out, whether by conduction, convection, or radiation, the total amount of energy stays the same. However, since it is spread out, less can be done with it.
4E/H4 ( Grades: 9-12 ): Chemical energy is associated with the configuration of atoms in molecules that make up a substance. Some changes of configuration require a net input of energy whereas others cause a net release.
4E/H6 ( Grades: 9-12 ): Energy is released whenever the nuclei of very heavy atoms, such as uranium or plutonium, split into middleweight ones, or when very light nuclei, such as those of hydrogen and helium, combine into heavier ones. For a given quantity of a substance, the energy released in a nuclear reaction is very much greater than the energy given off in a chemical reaction.
4E/H7 ( Grades: 9-12 ): Thermal energy in a system is associated with the disordered motions of its atoms or molecules. Gravitational energy is associated with the separation of mutually attracting masses. Electrical potential energy is associated with the separation of mutually attracting or repelling charges.
4E/H9 ( Grades: 9-12 ): Many forms of energy can be considered to be either kinetic energy, which is the energy of motion, or potential energy, which depends on the separation between mutually attracting or repelling objects.
4E/M1 ( Grades: 6-8 ): Whenever energy appears in one place, it must have disappeared from another. Whenever energy is lost from somewhere, it must have gone somewhere else. Sometimes when energy appears to be lost, it actually has been transferred to a system that is so large that the effect of the transferred energy is imperceptible.
4E/M2 ( Grades: 6-8 ): Energy can be transferred from one system to another (or from a system to its environment) in different ways: 1) thermally, when a warmer object is in contact with a cooler one; 2) mechanically, when two objects push or pull on each other over a distance; 3) electrically, when an electrical source such as a battery or generator is connected in a complete circuit to an electrical device; or 4) by electromagnetic waves.
4E/M3 ( Grades: 6-8 ): Thermal energy is transferred through a material by the collisions of atoms within the material. Over time, the thermal energy tends to spread out through a material and from one material to another if they are in contact. Thermal energy can also be transferred by means of currents in air, water, or other fluids. In addition, some thermal energy in all materials is transformed into light energy and radiated into the environment by electromagnetic waves; that light energy can be transformed back into thermal energy when the electromagnetic waves strike another material. As a result, a material tends to cool down unless some other form of energy is converted to thermal energy in the material.
4E/M4 ( Grades: 6-8 ): Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves.
4E/M6 ( Grades: 6-8 ): Light and other electromagnetic waves can warm objects. How much an object's temperature increases depends on how intense the light striking its surface is, how long the light shines on the object, and how much of the light is absorbed.
4F/E3 ( Grades: 3-5 ): Light travels and tends to maintain its direction of motion until it interacts with an object or material. Light can be absorbed, redirected, bounced back, or allowed to pass through.
4F/M1 ( Grades: 6-8 ): Light from the sun is made up of a mixture of many different colors of light, even though to the eye the light looks almost white. Other things that give off or reflect light have a different mix of colors.
4F/M2 ( Grades: 6-8 ): Something can be "seen" when light waves emitted or reflected by it enter the eye—just as something can be "heard" when sound waves from it enter the ear.
4F/M4 ( Grades: 6-8 ): Vibrations in materials set up wavelike disturbances that spread away from the source. Sound and earthquake waves are examples. These and other waves move at different speeds in different materials.
4F/M5 ( Grades: 6-8 ): Human eyes respond to only a narrow range of wavelengths of electromagnetic waves-visible light. Differences of wavelength within that range are perceived as differences of color.
4F/M8 ( Grades: 6-8 ): There are a great variety of electromagnetic waves: radio waves, microwaves, infrared waves, visible light, ultraviolet rays, X-rays, and gamma rays. These wavelengths vary from radio waves, the longest, to gamma rays, the shortest.
4G/H5ab ( Grades: 9-12 ): Magnetic forces are very closely related to electric forces and are thought of as different aspects of a single electromagnetic force. Moving electrically charged objects produces magnetic forces and moving magnets produces electric forces.
4G/H5c ( Grades: 9-12 ): The interplay of electric and magnetic forces is the basis for many modern technologies, including electric motors, generators, and devices that produce or receive electromagnetic waves.
4G/H6 ( Grades: 9-12 ): The nuclear forces that hold the protons and neutrons in the nucleus of an atom together are much stronger than the electric forces between the protons and electrons of the atom. That is why much greater amounts of energy are released from nuclear reactions than from chemical reactions.
4G/H7 ( Grades: 9-12 ): Electric currents in the earth's interior give the earth an extensive magnetic field, which we detect from the orientation of compass needles.
7G/M5 ( Grades: 6-8 ): The global environment is affected by national and international policies and practices relating to energy use, waste disposal, ecological management, manufacturing, and population.
8B/H7 ( Grades: 9-12 ): The development of new materials and the increased use of existing materials by a growing human population have led to the removal of resources from the environment much more rapidly than they can be replaced by natural processes. Disposal of waste materials has also become a problem. Solving these problems requires systematic efforts involving both social and technological innovations.
8C/E4 ( Grades: 3-5 ): Some people try to reduce the amount of fuels they use in order to conserve resources, reduce pollution, or save money.
8C/H2 ( Grades: 9-12 ): When selecting fuels, it is important to consider the relative advantages and disadvantages of each fuel.
8C/H3 ( Grades: 9-12 ): Nuclear reactions release energy without the combustion products of burning fuels, but the radioactivity of fuels and their by-products poses other risks.
8C/H4 ( Grades: 9-12 ): Industrialization brings an increased demand for and use of energy. Such usage contributes to having many more goods and services in the industrially developing nations but also leads to more rapid depletion of the earth's energy resources and to environmental risks associated with some energy resources.
8C/H6 ( Grades: 9-12 ): The useful energy output of a device—that is, what energy is available for further change—is always less than the energy input, with the difference usually appearing as thermal energy. One goal in the design of such devices is to make them as efficient as possible—that is, to maximize the useful output for a given input.
8C/H7 ( Grades: 9-12 ): During any transformation of energy, there is inevitably some dissipation of energy into the environment. In this practical sense, energy gets "used up," even though it is still around somewhere.
8C/H8 ( Grades: 9-12 ): Sunlight is the ultimate source of most of the energy we use. The energy in fossil fuels such as oil and coal comes from energy that plants captured from the sun long ago.
8C/M1 ( Grades: 6-8 ): Transformations and transfers of energy within a system usually result in some energy escaping into its surrounding environment. Some systems transfer less energy to their environment than others during these transformations and transfers.
8C/M10 ( Grades: 6-8 ): Some resources are not renewable or renew very slowly. Fuels already accumulated in the earth, for instance, will become more difficult to obtain as the most readily available resources run out. How long the resources will last, however, is difficult to predict. The ultimate limit may be the prohibitive cost of obtaining them.
8C/M11 ( Grades: 6-8 ): By burning fuels, people are releasing large amounts of carbon dioxide into the atmosphere and transforming chemical energy into thermal energy which spreads throughout the environment.
8C/M2 ( Grades: 6-8 ): Different ways of obtaining, transforming, and distributing energy have different environmental consequences.
8C/M3 ( Grades: 6-8 ): In many instances, manufacturing and other technological activities are performed at a site close to an energy resource. Some forms of energy are transported easily, others are not.
8C/M4 ( Grades: 6-8 ): Electrical energy can be generated from a variety of energy resources and can be transformed into almost any other form of energy. Electric circuits are used to distribute energy quickly and conveniently to distant locations.
8C/M6 ( Grades: 6-8 ): Industry, transportation, urban development, agriculture, and most other human activities are closely tied to the amount and kind of energy available. People in different parts of the world have different amounts and kinds of energy resources to use and use them for different purposes.
8C/M7 ( Grades: 6-8 ): # Energy is required for technological processes such as taking apart, putting together, moving around, and communicating.
8C/M8 ( Grades: 6-8 ): People have invented ingenious ways of deliberately bringing about energy transformations that are useful to them.
8C/P2 ( Grades: K-2 ): People burn fuels such as wood, oil, coal, or natural gas, or use electricity, to cook their food and warm their houses.
8D/M2 ( Grades: 6-8 ): Information can be carried by many media, including sound, light, and objects. In the 1900s, the ability to code information as electric currents in wires, electromagnetic waves in space, and light in glass fibers has made communication millions of times faster than mail or sound.
9C/E1 ( Grades: 3-5 ): Length can be thought of as unit lengths joined together, area as a collection of unit squares, and volume as a set of unit cubes.