Interaction/change

This is one of the unifying themes pervading all science disciplines. Some examples from science standards follow:

• Changes might occur, for example, in properties of materials, position of objects, motion, and form and function of systems. Interactions within and among systems result in change. Changes vary in rate, scale, and pattern, including trends and cycles.
• The interaction of matter, energy, and force governs all the systems in the universe.
• The structure of our universe is the result of interactions involving fundamental particles and basic forces.
• Interactions of organisms with each other and with the nonliving parts of their environment result in the flow of energy and cycling of matter throughout the system.
• Complex interactions among the different kinds of molecules in the cell cause distinct activities such as cell reproduction and growth.
• Substances can undergo physical changes that only alter the shape, form, volume, or density of the material but produce no change in chemical composition. Substances can also undergo chemical changes that produce new substances with different characteristics. Physical changes do not bring about the alterations in the properties of matter that chemical changes do.
• Things can be done to materials (cutting, heating, freezing, etc.) to change their appearance and some of their properties. Materials respond differently to changes; most changes occur faster at higher temperatures.
• The surface of the earth changes. Some changes are due to slow processes, such as erosion and weathering, and some changes are due to rapid processes, such as landslides, volcanic eruptions, and earthquakes. Weather changes from day to day and over the seasons.
• Pollution is a change in the environment that can influence the health, survival, or activities of organisms, including humans.
• Technological changes are often accompanied by social, political, and economic changes that can be beneficial or detrimental to individuals and to society.
• Changes in systems can be quantified. Evidence for interactions and subsequent change and the formulation of scientific explanations are often clarified through quantitative distinctions--measurement.

Energy

• Energy manifests itself in many forms: mechanical (potential and kinetic), chemical, electrical, magnetic, nuclear, and radiant energy.
• Energy can be transformed from one form to another.
• Examples of energy transformations:
• Food has energy that is changed by the body cells into energy used to grow, think, and play. When a light bulb is on, electrical energy changes into light energy and heat energy. Heat can be produced when things rub together. Heat is also produced by most things that give off light such as light bulbs, televisions, or the sun. When warmer objects contact cooler objects there is a transfer of energy; warmer objects lose energy and the cooler ones gain energy until they are all at the same temperature.
• Objects and substances can store energy physically and chemically. A stretched rubber band and a compressed spring have stored energy. Batteries, food, and gasoline are also examples of substances or things that have stored chemical energy. There is also energy associated with movement or motion.
• When energy is transferred from one object to another, or when one kind of energy changes to another, work and/or heat are involved.
• In a closed system, the total amount of energy is always the same. When mass and energy are thought of as different forms of the same thing, the sum of the mass plus the energy of a closed system is always the same.
• Matter can be converted to energy. Enormous amounts of energy can be involved in this conversion process.
• The interaction of matter, energy, and force governs all the systems in the universe.

Instruments

• This theme involves the use of appropriate tools and techniques to gather, analyze, and interpret data. Tools help scientists make better observations, measurements, and equipment for investigations.
  
• It also involves the use of instruments and techniques that enable observations of objects and phenomena that are otherwise unobservable due to factors such as quantity, distance, location, size, and speed.
  
• It includes the development of skills in the use of computers and calculators for conducting investigations. The use of computers for the collection, summary, and display of evidence.
  
• Scientific tools such as microscopes, balances, and other instruments facilitate inquiry and problem-solving strategies. Because of science's historical reliance on evidence, great value is placed on the development of better instruments and techniques of observation.
  
• For students, the use of simple equipment and tools to gather data and extend the senses. In early years, students develop simple skills, such as how to observe, measure, cut, connect, switch, turn on and off, pour, hold, tie, and hook. Beginning with simple instruments, students can use rulers to measure the length, height, and depth of objects and materials; thermometers to measure temperature; watches to measure time; beam balances and spring scales to measure weight and force; magnifiers to observe objects and organisms; and microscopes to observe the finer details of plants, animals, rocks, and other materials.

Structure of matter

• All matter occupies space and has mass. Mass is the amount of matter in an object. Matter has observable properties that can be measured.
• Matter exists in three common states (solid, liquid, and gas) depending on temperature and pressure. Each state has characteristic properties.
• Scientists have demonstrated that, despite differences in shape, color, texture, and density, all matter is really composed of building blocks called atoms, that are in constant motion. Substances that are made of the same kind of atoms are called elements. Different kinds of atoms can combine to form simple molecules of substances, such as water, as well as the most complex molecules in the universe, such as proteins.
• Atoms are made up of many subatomic particles including electrons, protons, and neutrons. These subatomic particles seem to be made of even smaller particles.
• Elements contain only one kind of atom. Other substances are made up of two or more different elements in which the atoms group together to form molecules. A substance that is made up of the same molecules is a compound. Substances can undergo physical changes that only alter the shape, form, volume, or density of the material but produce no change in chemical composition. Substances can also undergo chemical changes that produce new substances with different characteristics. Physical changes do not bring about the alterations in the properties of matter that chemical changes do.
• A substance has characteristic properties, such as density, a boiling point, and solubility, all of which are independent of the amount of the sample. A mixture of substances often can be separated into the original substances using one or more of the characteristic properties.
• Substances react chemically in characteristic ways with other substances to form new substances (compounds) with different characteristic properties. In chemical reactions, the total mass is conserved. Substances often are placed in categories or groups if they react in similar ways; metals is an example of such a group.
• Some atoms have heavier unstable nuclei that decay, spontaneously producing wavelike radiation, short-lived particles, and/or simpler atoms.
• Evidence indicates that matter has properties of both particles and waves.

Patterns in nature

• This is one of the unifying themes pervading all science disciplines. Some examples follow:
• Most natural events occur in consistent patterns that are comprehensible through careful, systematic study.
• All life forms, including human organisms, have patterns of structure, development, growth, and maintenance that distinguish them from nonliving things.
• Using their intellect and aided by instruments that extend the senses, scientists can discover patterns in nature.
• Objects in the sky have patterns of movement. The sun, for example, appears to move across the sky in the same way every day, but its path changes slowly over the seasons. The moon moves across the sky on a daily basis much like the sun. The observable shape of the moon changes from day to day in a cycle that lasts about a month.
• An organism's patterns of behavior are related to the nature of that organism's environment, including the kinds and numbers of other organisms present, the availability of food and resources, and the physical characteristics of the environment.

Systems

This is one of the unifying themes pervading all science disciplines. Some examples follow:

• A system is an organized group of related objects or components that form a whole. Systems can consist, for example, of organisms, machines, fundamental particles, galaxies, ideas, numbers, transportation, and education. Systems have boundaries, components, resources flow (input and output), and feedback.
• The interaction of matter, energy, and force governs all the systems in the universe.
• Earth is a unique planet with four major interacting systems: lithosphere (earth), atmosphere (air), hydrosphere (water), and biosphere (life). Conditions that exist in one system, such as ice (frozen water), influence the conditions that exist in the other systems.
• Earth's systems as well as organisms are the result of a long, continuous evolutionary history. Earth systems are interactive; for example, the present atmosphere was created and is maintained by the photosynthetic process of green plants over billions of years.
• Biological systems obey the same conservation laws as physical systems. Complex interactions among the different kinds of molecules in the cell cause distinct activities such as cell reproduction and growth.
• The body has basic systems. If these systems are affected by diseases, the body has several ways to defend itself against them.
• The natural process of entropy tends to increase the disorder of a system. A highly organized system will inevitably proceed to a state of disorder and chaos unless energy is used to reestablish order.
• In a closed system, the total amount of energy is always the same. When mass and energy are thought of as different forms of the same thing, the sum of the mass plus the energy of a closed system is always the same.

Space-Time relationships

• This theme involves the description of spatial relationships and their change with time. It includes the study of shapes, symmetry, motion, and rate of change. General categories include: shapes; time; direction and spatial arrangement; and motion and speed.
• Objects are made of different materials that have many properties (color, size, shape, density, and volume) which can be compared and measured.
• All time is measured by a movement in space. Some motions keep recurring. Examples are a pendulum, a vibrating spring, and an object spinning in a circle. These recurring motions lend themselves to measuring time.
• Understanding the concepts of time and size is critical when exploring interacting Earth processes. Lightning, for example, can strike in a split second, a dramatic contrast to the amount of time that passes before the shifting of Earth's plates alter the landscape.
• The motion of an object can be described by its position, direction of motion, and speed. That motion can be measured and represented on a graph.
• Types of motion include constant speed in a straight line, constant speed in a circle, acceleration in a straight line, and acceleration in a circular path. Many complex motions can be considered as a combination of these motions. Important properties of motion include position in space, distance traveled, displacement, speed, velocity, and acceleration.
• The description of the motion of an object is affected by the frame of reference used to view that motion.
• Most objects in the solar system are in regular and predictable motion. Those motions explain such phenomena as the day, the year, phases of the moon, and eclipses.

Statistical view

• Scientists communicate with oral and written words, diagrams, maps, graphs, mathematical equations, and many kinds of visual demonstrations.
• Students should develop general abilities, such as systematic observation, making accurate measurements, and identifying and controlling variables. They should also develop the ability to clarify their ideas that are influencing and guiding the inquiry, and to understand how those ideas compare with current scientific knowledge. Students can learn to formulate questions, design investigations, execute investigations, interpret data, use evidence to generate explanations, propose alternative explanations, and critique explanations and procedures.

Tradeoffs

Examples of this theme include the following:

• Perfectly designed solutions do not exist. All technological solutions have tradeoffs, such as safety, cost, efficiency, and appearance. Engineers often build in back-up systems to provide safety. Risk is part of living in a highly technological world. Reducing risk often results in new technology.
• Society must make tradeoffs in choosing energy sources for personal and industrial use. People should consider energy efficiency when they buy energy-using appliances and vehicles; costs and risks to society and the environment vary according to the sources and uses of energy.
• Technological solutions are temporary; technologies exist within nature and so they cannot contravene physical or biological principles; technological solutions have side effects; and technologies cost, carry risks, and provide benefits.
• New technologies often will decrease some risks and increase others.
• Risk analysis considers the type of hazard and estimates the number of people that might be exposed and the number likely to suffer consequences. The results are used to determine the options for reducing or eliminating risks.
• Individuals can use a systematic approach to thinking critically about risks and benefits. Examples include applying probability estimates to risks and comparing them to estimated personal and social benefits.