The details on the fields of science provided below indicate themes that can be explored within major topic areas as well as brief examples of developmentally appropriate sample questions that can form the basis for assessment exercises.

Earth Science

Earth science is the study of the planet Earth’s composition, processes, environments, and history, focusing on the solid Earth (lithosphere) and its interactions with air (atmosphere) and water (hydrosphere). In Earth science, the content to be assessed centers on objects (including bodies and materials and their composition, features, and structures) as well as processes and events that are relatively accessible or visible. The content includes objects such as soil, minerals, rocks and rock outcrops, fossils, rain, clouds, the Sun, and the Moon; processes such as erosion, deposition, weather, and climate; and events such as volcanic eruptions, earthquakes, and storms.

The Solar System

Earth/Moon/Sun:

• observable evidence (Patterns of Change)

• description and models (Systems, Models)

Students should understand that the apparent daily motions of the Sun, Moon, planets, and stars are due to the rotation of the Earth about its axis every 24 hours. This rotation produces the Earth’s night-and-day cycle. They should also understand that the Earth’s 1-year revolution around the Sun changes how sunlight falls on one part or another of the Earth because of the tilt of the Earth’s axis, thus producing seasonal variations in climate. They should know that the combination of the Earth’s motion and the Moon’s own orbit around the Earth, once in about 28 days, results in the phases of the Moon.

The Earth and the Forces That Shape It

With respect to the Earth, the NAEP Science Assessment should center on the following concepts:

Climate (Patterns of Change):

• water cycle and ground water (Systems)

• pollution capacity (Systems, Models)

• interior effects (Models, Systems, Patterns of Change)

  —crustal plates

  —rock cycles and strata

Exterior Effects (Systems, Patterns of Change):

• weathering

• plants, animals, and civilization

Students should understand that the Earth is a unique member of this solar system but could be replicated in other galaxies in the universe; that it is at least 4.5 billion years old and is a complex planet with several interacting systems; and that these systems have evolved through time and changes in them occur over periods that range from microseconds to millions of years and vary from subatomic to astronomical. Students should also understand that the Earth’s systems contain a variety of renewable and nonrenewable resources that sustain life (American Geological Institute, 1991).

Climate: Atmosphere and Hydrosphere

The atmosphere is the gaseous envelope that surrounds the Earth. It is continuously in motion, circulating in complex but regular patterns and driven by direct and stored solar energy. There are strong interactions between the atmosphere and the hydrosphere that determine weather and climate, profoundly influencing human and all other life. Desired learning goals follow.

Grade 4:

• Students are able to communicate what is special about air. What do their senses tell them about the air? What needs air?

• Students are able to offer simple explanations for how the weather changes. How do people know when weather changes? How can changing weather conditions be measured?

Grade 8:

• Students know about basic weather-related phenomena (for example, tornadoes, hurricanes, drought, and acid precipitation).

• Students know that relatively small changes in global temperatures can have dramatic effects on the Earth.

• Students can access climatological information bases via computers and use other means to extract useful information.

• Students can read a weather chart and extract basic information.

• Students understand and can use simple instruments, such as barometers, that measure basic phenomena related to weather Students will make a barometer and/or know how it works.

Grade 12:

• Generally, 12th-grade students are able to connect relationships between atmospheric phenomena and long-term effects.

• They understand that much of what determines the details of the weather depends on phenomena such as sea breezes, thunderstorms, tornadoes, and wind shear.

• They understand how scientists can monitor atmospheric events over time (for example, how products of pollution and carbon dioxide affect the poles).

• Students are able to discuss and relate causes and possible solutions to their consequences and tradeoffs.

Water Cycle and Ground Water

Desired learning goals follow.

Grade 4:

• Students understand that water exists not only on the surface of the Earth, but beneath it as well.

• Students understand that water is able to change the shape of the Earth. They can demonstrate their knowledge in two ways: by interpreting common local land features such as rivers, streams, mountain slopes, and delta deposits, or by designing simple models that illustrate their interpretations.

• Students understand that most of the Earth’s surface is covered by water.

• Students know how waters of the Earth circulate. They can answer questions concerning where water is found; how water enters and leaves the atmosphere; and how water can be used more wisely.

Grade 8:

• Students know and demonstrate why water is special. What properties make water special? Where is water found: in the air, on Earth, and under the ground?

• Students know that the oceans provide habitats for a wide variety of plant life and animal life.

• Students can discuss some common problems that concern water, for example, its availability in their areas, shortages, relationship to supply and demand, and the effects of overpopulation on the availability and quality of potable water.

• Students are able to understand common interactive cycles such as the water cycle, nitrogen cycle, and carbon cycle.

• Students are familiar with some of the ways scientists explore the water environment.

Grade 12:

• At grade 12, students are able to explain how water (or the lack of it) relates to their immediate state, city, or area.

• They can discuss national issues related to water, such as acid precipitation and the effects of global warming.

• They are able to understand how common cycles affect the climate of the area where they live.

• Students know how to find answers to problems relating to how laws affect the use of water, as well as what hazards are associated with water and how they can be mitigated.

Interaction of Earth’s Systems

Desired learning goals follow.

Grade 4:

• Students understand the ways in which the Earth relates to the Sun (for example, periodicity, seasons, and the night-and-day cycle).

• Students know about tides with respect to the Earth, Moon, and Sun.

• Students understand basic facts about volcanoes and glaciers.

• Students understand how rocks and minerals can be investigated, what they are made of, and how they form.

Grade 8:

• Students are able to understand how earthquake occurrences are recorded and note some positional regularities.

• Students are able to connect short-term changes in climate with volcanic activity.

• Students can discuss changes that have occurred in water levels, global temperature, and climate zones over the eons. They can advance some hypotheses as to why these changes have occurred.

• Students can identify how and where energy is obtained from the Earth; Earth materials that people use and where to find them; and the advantages and disadvantages of using the Earth’s resources.

• Students in grade 12 can connect "the zone of fire" with plate tectonics. They understand how sliding plates cause sudden Earth movements.

• They can discuss issues related to Earth systems (for example, why continents move, that they have not always been arranged the way they are now, and how human activity affects Earth systems).

• Students can access data from more than one data source to develop an environmental impact statement for their region/town/block.

• Students can discuss problems associated with agriculture and the lithosphere and relate these problems to changing atmospheric conditions.

The physical science component of the 2005 NAEP Science Assessment should probe the following major topics: matter and its transformations, energy and its transformations, and the motion of things. Each topic is detailed below, together with some examples of topics appropriate for assessment at the different grade levels.

Matter and Its Transformations

With respect to matter and its transformations, the 2005 NAEP Science Assessment should center on the following concepts:

"Many From Few:"

• diversity of materials (Models)

• classifications and types of materials (Patterns of Change)

• particulate nature of matter (Models)

Temperature and States of Matter:

• uses of materials

  —properties and uses

  —modifying properties by mixing, processing, and reacting (Patterns of Change, Models)

  —synthesis of materials with new properties (Patterns of Change, Models)

Resource Management:

• resource depletion and substitute materials (Models)

• disposal and recycling (Systems)

As they advance in science, students should come to understand that the basic premise of the modern theory of matter is that materials consist of a limited number of different kinds of atoms (elements) that join together in different configurations to form substances. Thus, when substances react to form new substances, the elements composing them combine in new ways and the properties of the substances created by the new combinations may be very different from those of the old. Almost every substance can exist in a variety of states (solid, liquid, and gaseous) depending on temperature and pressure.

Patterns within the structure of matter have been elegantly described in the periodic table, an outstanding example of a model that provides a systematic view of matter and its interactions. Changes in temperature and changes in state represent a category of physical change among substances within the realm of matter and energy.

An understanding of the particulate nature of matter can be assessed through the identification of types of materials; for example, "mystery powders" or the equivalent at the elementary level. The effects of temperature and heat energy on systems are exemplified in how refrigerators work, how and why ice cubes melt, and how metallic fuses work. Some practical areas of human activity (for example, cooking and much of the modern chemical industry) and processes (transport of materials in biological systems) are related both to the nature of matter and to the effects of external factors on its behavior. All these topics can provide rich assessment exercises.

The properties of matter determine the uses to which particular materials are put by manufacturers, engineers, and others involved in technology. Materials can be physically combined or processed to serve human needs. Modern materials technology has focused increasingly on the synthesis of materials with entirely new properties. Chemical changes are typically involved, and the properties of the new materials (such as plastics and ceramics) may be entirely different from those of their components.

The growth of technology has led to the use of some materials from the environment (for example, forests, ore deposits, and petroleum) much more rapidly than they can be replaced by natural processes. There is a continuing search for substitute materials, and, in many cases, they have been found or invented.

Disposal of used materials has become an increasing problem. Some used materials, such as food scraps and waste paper, can be returned safely to the environment; however, as the population grows, that task becomes more difficult and expensive. Other materials, such as aluminum scrap and glass, can be recycled, with resulting savings in energy and resources. Some materials, such as plastics, are not easily recycled, nor do they degrade quickly when returned to the environment. Other used materials—radioactive waste being the most dramatic but not the only example—are so hazardous for such a long time that it is not clear how best to dispose of them. This issue has become the subject of widespread debate and controversy. Solving these problems of disposal will require systematic efforts that include both social and technological innovations. Assessment questions dealing with the scientific and technological issues involved in resource management are appropriate for grades 8 and 12.

Energy and Its Transformations

With respect to energy and its transformations, the 2005 NAEP Science Assessment should center on the following concepts:

Forms of Energy:

• energy transformation (qualitative) and audits (quantitative):

  —living systems

  • plants

  • animals

  • protista

  —natural physical systems

  —artificial (human-constructed) systems

Energy Sources and Use:

• quantity and kind

• distribution (Patterns of Change)

• energy conversions, heat gain/loss, and efficiency (Patterns of Change, Models)

• slowing depletion of energy sources, or conservation

• costs, implications, advantages, risks, and availability (Patterns of Change)

Students need to understand that energy is conserved. Within a system, whenever the quantity of energy in one place or form changes, the quantity of energy in another place or form increases or decreases by a similar quantity, and the total energy remains the same. Thus, if no energy leaks in or out across the boundaries of a system, the total energy of all the different forms in the system will not change, no matter what kinds of changes occur within the system.

Energy transformations usually result in producing some thermal energy (heat), which leaks away by radiation or conduction (for instance, from engines, electrical wires, hot water tanks, human bodies, or stereo systems) and becomes unavailable for further transformations. Thus, the total quantity of energy available for transformation usually decreases.

Students need to develop an understanding of the more general principle that natural processes occur in the direction of increasing the total disorder of the system and its surroundings. Although some subsystems do increase in orderliness (such as the freezing of water to form ice), at the same time, another part of the system or a connected system is becoming more disordered. The cells of a human organism, for example, are always busy increasing order by building complex molecules and body structure. This occurs at the cost of increasing disorder even more through processes such as breaking down the molecular structure and order of food that is eaten and warming up surroundings.

Energy transformations occur both naturally and in devices constructed by humans.

Naturally Occurring Transformations:

• solar energy into stored energy such as starches, fats, and proteins

• solar energy into heat

• potential energy into kinetic energy (the potential energy of roller coasters at the top of a hill converting to kinetic energy on the way to the bottom)

Transformations Occurring in Human Artifacts:

• electric mixer converts electrical energy into mechanical energy

• hair dryer converts electrical energy into heat energy

• automobile converts chemical energy into mechanical energy

Radiant energy from the Sun is the ultimate source of most of the energy we use. It becomes available to us in several ways. The energy of sunlight is captured directly in plants, which then may be eaten; it also heats the air, land, and water, causing wind and rain. For much of history, burning wood was the most common source of intense energy for cooking, heating dwellings, and running machines. Most of the energy used today is derived from burning fossil fuels, which contain stored solar energy that plants collected over millions of years. A new source of energy is the fission of the nuclei of heavy elements, which releases an immense quantity of energy in relation to the mass of material used when compared with the burning of fossil fuels. In nuclear reactors, the energy generated is used mostly to heat water into steam, which drives electric generators.

Humans use energy for technological processes such as transporting, manufacturing, communicating, and getting raw materials, then working with them, and finally recycling them. Students need to appreciate that different sources of energy and ways of using them involve different costs, implications, and risks. Some resources will continue to be available indefinitely; others can be made selfrenewing, but only at a limited rate. Fuels like coal, oil, natural gas, and uranium will become more difficult to obtain as the most readily available sources become depleted. New technology may make it possible to use the remaining sources better; the ultimate limitation may be prohibitive cost rather than complete disappearance.

Students should know that the depletion of nonrenewable energy sources can be slowed by both technical and social means. Technical means include maximizing the advantages realized from a given input of energy through good design of the transformation device, insulation to restrict heat flow (insulating hot water tanks), or additional work with the heat as it dissipates. Social means include government, which may restrict low-priority uses of energy or establish requirements for efficiency (as in automobile engines) or insulation (as in house construction). Individuals may also make energy efficiency a consideration in their own choice and use of technology (for example, turning out lights and driving high-efficiency cars), either to conserve energy as a matter of principle or to reduce their personal long-term expenses. Students need to appreciate that there will always be tradeoffs. For example, better insulated houses restrict ventilation and thus may increase the indoor accumulation of pollutants.

The bases for these energy-related concepts should be laid in elementary school science. The following examples illustrate appropriate activities that can be used to formulate assessment exercises for students in grade 4:

• The student gives examples from his/her own experience of heat energy and light energy changing a system.

• The student identifies the source of energy for a familiar system (animal, plant, car, electric appliance) and describes some of the energy conversions that take place in each system.

• The student identifies the energy stored in a stretched rubber band and in a stretched or compressed spring as potential energy. The student explains that to store potential energy in a rubber band or in a spring, he/she must exert a force to stretch the rubber band, or to stretch or compress the spring.

• Given pictures of several situations, some of which depict a force being exerted or work being done and some of which do not, the student identifies those pictures in which a force is being exerted.

• The student explains, using the words fuel and energy in context, why a candle goes out when the wax is used up.

• The student writes a short essay on how his/her life would be different if all the coal and petroleum on Earth were used up.

With respect to this topic area, the 2005 NAEP Science Assessment Framework should center on the following concepts:

Motion:

• force and changes in position and motion

• action and reaction

Waves:

• vibrations and waves as motion summaries

• general wave behavior

• electromagnetic radiation

• effects of wavelength

• interactions of electromagnetic radiation with matter

Reference Frames

Grade 4

Everything moves: bicycles, cars, and trains; the stars, planets, and moons; the Earth, its surface, and everything on its surface; and all living things and every part of all living things. Positions of things may be described, but positions may change. Monitoring changes in time yields information about speed.

Grade 8

No special point in space can serve as a reference for all other motion. All motion is relative to whatever point or object is chosen.

Forces and Motion

Grade 4

Changes in motion (that is, changes in speed or direction) are due to the effects of forces.

Grade 8

Any object maintains a constant speed and direction of motion (including being at rest) unless an unbalanced outside force acts on it. When an unbalanced force does act on an object, the object’s motion changes. Depending on the direction of the force relative to the direction of motion, the object may change its speed (a falling apple), its direction of motion (the Moon in its curved orbit), or both (a fly ball). The greater the extent of the unbalanced force, the more rapidly a given object’s speed or direction of motion changes. In most familiar situations, friction between surfaces brings forces into play that complicate the description of motion, although the basic principles still apply.

Grade 12

The more massive an object is, the less rapidly its speed or direction changes in response to any given force. Whenever A exerts a force on B, B exerts an equal force back on A, but in the direction opposite of the force exerted by A.

Vibrations and Waves

Grade 4

Some motions can be described most conveniently in summary descriptions of the pattern of motion, such as vibrations and waves. Vibrations may set up a traveling disturbance that spreads away from its source.

Grade 8

Vibration involves parts of a system moving back and forth in much the same place, so the motion can be summarized by how frequently it is repeated and by how far the parts of a system are displaced during the cycle. Vibration may move through a system as a wave. Wave behavior can be described in terms of speed, wavelength, and frequency. Wavelength can help determine how a wave interacts with things: how well it is transmitted, absorbed, reflected, or diffracted.

Grade 12

Apparent change in wavelength can provide information about relative motion. The ways in which shock waves of different wavelengths travel through and reflect from layers of rock are important clues to the structure of the Earth’s interior.

Light as Waves

Grade 4

White light is made up of all different colors of light. Things appear to have different colors because they reflect or scatter the light of some colors more than others.

Grade 8

Light behaves in many ways like waves: changing direction, bouncing off surfaces, spreading out, speeding up, slowing down, and changing wavelength.

Grade 12

The interaction of electromagnetic waves with matter varies greatly with wavelength. Thus, different but somewhat overlapping electromagnetic ranges have been given distinctive names: radio waves, microwaves, radiant heat or infrared radiation, visible light, ultraviolet light, x-rays, and gamma rays. Materials that allow one range of wavelengths to pass through them may completely absorb others. For example, some gases in the atmosphere, including carbon dioxide and water vapor, are transparent to much of the incoming sunlight but not to the infrared radiation emitted by the warmed surface of the Earth. Consequently, heat energy is trapped in the atmosphere. The temperature of the Earth rises until its total radiation output reaches a state of balance with the total radiation input from the Sun.

Life Science

The fundamental goal of life science is to attempt to understand and explain the nature of life. During the 20th century, the thrust of biological research changed its focus from descriptive natural history to experimental science, with most biological investigations conducted within the theory of evolution. The major concepts to be assessed in the life sciences (with evolution as the central, unifying theory) are listed below and developed further in the grade-level descriptions that follow.

Cells:

• information transfer

• energy transfer

• cellular communication

Organisms:

• reproduction, growth, and development

• life cycles

• functions and interactions of systems within organisms

Ecology:

• the interdependence of life: populations, communities, and ecosystems

Evolution:

• the diversity of life on Earth

• genetic variation within a species

• adaptation and natural selection

• changes in diversity over time

Students’ understanding of life science concepts develops gradually as they proceed from grade 4 to grade 8 to grade 12. A description of the developmentally appropriate concepts that should be understood at each grade follows.

Grade 4

Organisms:

• As some animals grow, they look pretty much the same, they just increase in size. As other animals grow, they change from one form to another form that looks very different. They may change form several times before they become adults.

• Only adults can reproduce, but not all young animals survive long enough to become adults.

• Many activities go on inside the body that cannot be seen. When something happens in one part of the body, it affects what goes on in other parts of the body.

Ecology:

• Plants make their own food with sunlight, water, and air.

• Some animals eat plants; some of these animals are in turn eaten by other animals.

• Plants and animals get energy and building materials from their food.

Evolution:

• There are different kinds of plants and animals on Earth and in the sea.

• There are differences among individuals of the same kind of plant or animal.

• Children of the same parents are somewhat alike and somewhat different.

Organisms:

• Different systems of the body have different functions; however, the functioning of each system affects other systems.

• Interactions among systems are complex. These interactions maintain a fairly stable operation of the entire system that can resist disturbance from within or without.

• Interaction with other organisms (especially microorganisms) is important to maintain health or cause disease. Avoiding or killing harmful microorganisms can prevent disease.

Ecology:

• Plants use energy in sunlight to assemble food molecules from water and carbon dioxide.

• Plants and animals break down food molecules to obtain food energy.

• The source of energy and materials for all animals is plants.

• The pattern of "what eats what" in a community can be complex.

Evolution:

• The organisms that survive long enough to reproduce may be different in some ways from others in a population that do not survive long enough to reproduce; their offspring may inherit the anatomical, chemical, and/or behavioral characteristics that enabled the parents to survive.

• Gradually, over many generations, organisms with favorable characteristics may crowd out other organisms in the population that do not have these characteristics.

• Scientists believe that these processes, operating over very long periods of time, have resulted in the diversity of organisms that can be seen on Earth today.

• Adaptation may be to either the living or nonliving components of the environment.

Cells:

• Every cell contains a recipe for running the cell, coded in deoxyribonucleic acid (DNA) molecules; the code mainly specifies how to put proteins together.

• During cell reproduction, the information in the DNA code is passed on to the next generation of cells.

• Proteins control most of what goes on within cells and within the body.

• There are interactions among the cells of an organism; molecules from one cell affect what goes on inside other cells.

• In plant cells, energy from sunlight is transformed into chemical energy during photosynthesis; in plant and animal cells, the chemical energy stored in food molecules is released during digestion and produces heat. Some of this released energy is used to build new molecules.

Organisms:

• Separate parts of the body can communicate with one another using electrical or chemical signals.

• Complex interacting systems include feedback that tends to produce cycles of activities within the body.

• In organisms that reproduce sexually, each parent passes on one-half of its DNA information to each of its offspring; therefore, half of the DNA in each cell of an organism came from one parent, and half from the other parent.

Ecology:

• Interactions between living and nonliving components affect how ecosystems function as a whole.

• A change in one component of an ecosystem affects other components of an ecosystem. These components in turn react in a way that will restore the ecosystem to its original condition.

• Often, changes in one component of an ecosystem will have effects on the entire system that are difficult to predict.

• The size of a population and the rate of growth of a population are determined largely by the survival rate, reproductive rate, and death rate of the organisms in the population. Predictions about changes in the size or rate of growth of a population can be described using mathematical models.

Evolution:

• Recombination and mutation are the raw materials for new traits upon which natural selection acts.

• When the environment changes, different characteristics may become important for survival; that is, different adaptations are important for survival in different environments.

• Some descendants are so different from other descendants that they can no longer breed with each other.

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Science Framework for the 2005 National Assessment of Educational Progress