Most food comes from farms either directly as crops or as the animals that eat the crops.
Learning Goal 1b
To grow well, plants need enough warmth, light, and water. Crops must be protected from weeds and pests.
Learning Goal 2
Part of a crop may be lost to pests or spoilage.
Learning Goal 3
A crop that is fine when harvested may spoil before it gets to consumers.
Learning Goal 4a
Machines improve what people get from crops by helping in planting and harvesting.
Learning Goal 4b
Machines keep food fresh by packaging and cooling and move the food long distances from where it is grown to where people live.
For Grades: 3-5
Learning Goal 1a
Some plant varieties and animal breeds have more desirable characteristics than others, but some may be more difficult or costly to grow.
Learning Goal 1b
The kinds of crops that can grow in an area depend on the climate and soil.
Learning Goal 1c
Irrigation and fertilizers can help crops grow in places where there is too little water or the soil is poor.
Learning Goal 2
Damage to crops by rodents, weeds, or insects can be reduced by using poisons, but their use may harm other plants or animals.
Learning Goal 3
Heating, salting, smoking, drying, cooling, and air-tight packaging are ways to slow down the spoiling of food by microscopic organisms so food can be stored longer before being used.
Learning Goal 4
Modern technology has increased the efficiency of agriculture so that fewer people are needed to work on farms than ever before.
Learning Goal 5
Places too cold or dry to grow certain crops can obtain food from places with more suitable climates. Much of the food eaten by Americans comes from other parts of the country and the world.
For Grades: 6-8
Learning Goal 1
Early in human history, people changed from hunting and gathering to farming. This shift allowed changes in the division of labor between men and women and between children and adults and led to the development of new patterns of government.
Learning Goal 2
People control some characteristics of plants and animals they raise by selective breeding and by preserving varieties of seeds (old and new) to use if growing conditions change.
Learning Goal 3ac
In agriculture, as in all technologies, there are always trade-offs to be made. Specializing in one crop may risk disaster if changes in weather or increases in pest populations wipe out that crop. Also, the soil may be exhausted of some nutrients, which can be replenished by rotating the right crops.
Learning Goal 3b
Getting food from many different places makes people less dependent on weather in any one place yet more dependent on transportation and communication among far-flung markets.
Learning Goal 4
With improved technology, only a small fraction of workers in the U.S. actually plant and harvest the products that people use. Most workers are engaged in processing, packaging, transporting, and selling what is produced.
For Grades: 9-12
Learning Goal 1
New varieties of farm plants and animals have been engineered by manipulating their genetic instructions to produce new characteristics.
Learning Goal 2
Government sometimes intervenes in matching agricultural supply to demand to ensure a stable, high-quality, and inexpensive food supply. Regulations are often also designed to protect farmers from abrupt changes in farming conditions and from competition from other countries.
Learning Goal 3a
Agricultural technology requires trade-offs between increased production and environmental harm and between efficient production and social values.
Learning Goal 3b
In the 1900s, agricultural technology led to a huge shift of population from farms to cities and to a great change in how people live and work.
Subchapter B
Materials and Manufacturing
For Grades: K-2
Learning Goal 1
Some kinds of materials are better than others for making any particular thing. Materials that are better in some ways, such as stronger or cheaper, may be worse in other ways, such as heavier or harder to cut.
Learning Goal 2
Several steps are usually involved in making things.
Learning Goal 3
Tools are used to help make things, and some things cannot be made at all without tools. Different tools have different uses.
Learning Goal 4
Some objects can be used over again.
For Grades: 3-5
Learning Goal 1
Naturally occurring materials such as wood, clay, cotton, and animal skins may be processed to change their properties.
Learning Goal 2
Humans have produced a wide variety of materials, such as steel, plastic, and nylon, that do not appear in nature.
Learning Goal 3
Discarded products contribute to the problem of waste disposal.
Learning Goal 3b
Sometimes it is possible to use the materials from discarded products to make new products, but materials differ widely in the ease with which they can be recycled.
Learning Goal 4
Although many things are still made by hand in some parts of the world, almost everything in the most technologically developed countries is now produced using machines that are automated. By using machinery, the time required to make a product and its cost can be greatly reduced.
For Grades: 6-8
Learning Goal 1
The choice of materials for a job depends on their properties.
Learning Goal 2
Manufacturing usually involves a series of steps, such as designing a product, obtaining and preparing raw materials, processing the materials mechanically or chemically, and assembling the product. All steps may occur at a single location or may occur at different locations.
Learning Goal 3
Advances in manufacturing processes can reduce costs and improve products.
Learning Goal 4
Automation, including the use of robots, has changed the nature of work in most fields, including manufacturing. As a result, the demand for workers with some knowledge and skills has decreased while the demand for workers with other knowledge and skills has increased. Furthermore, as the pace of innovation has increased, workers have needed to learn new skills throughout their careers.
Learning Goal 5
Efforts to find replacements for existing materials are driven by an interest in finding materials that are cheaper to obtain or produce or that have more desirable properties.
Learning Goal 6
Some materials, such as plastics, are synthesized in chemical reactions that link atoms together in long chains. Plastics can be designed to have a variety of different properties for a variety of uses.
Learning Goal 7
Machines can be used to manufacture parts that are nearly identical. The use of these interchangeable parts allows for more efficient assembly as time is not needed to customize the fit of different parts.
For Grades: 9-12
Learning Goal 1
Manufacturing processes have been changed by improved tools and techniques based on more thorough scientific understanding, increases in the forces that can be applied and the temperatures that can be reached, and the availability of electronic controls that make operations occur more rapidly and consistently.
Learning Goal 2
Waste management includes considerations of quantity, safety, degradability, and cost. It requires social and technological innovations, because waste-disposal problems are political and economic as well as technical.
Learning Goal 4
Increased knowledge of the properties of particular molecular structures helps in the design and synthesis of new materials for special purposes.
Learning Goal 5
Objects made up of a small number of atoms may exhibit different properties than macroscopic objects made up of the same kinds of atoms.
Learning Goal 6
Groups of atoms and molecules can form structures that can be measured in billionths of a meter. The properties of structures at this scale (known as the nanoscale) and materials composed of such structures, can be very different than the properties at the macroscopic scale because of the increase in the ratio of surface area to volume and changes in the relative strengths of different forces at different scales. Increased knowledge of the properties of materials at the nanoscale provides a basis for the development of new materials and new uses of existing materials.
Learning Goal 7
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.
Subchapter C
Energy Sources and Use
For Grades: K-2
Learning Goal 2
People burn fuels such as wood, oil, coal, or natural gas, or use electricity, to cook their food and warm their houses.
For Grades: 3-5
Learning Goal 1
Moving air and water can be used to run machines.
Learning Goal 2
Sunlight is used to run many devices.
Learning Goal 4
Some people try to reduce the amount of fuels they use in order to conserve resources, reduce pollution, or save money.
For Grades: 6-8
Learning Goal 1
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.
Learning Goal 2
Different ways of obtaining, transforming, and distributing energy have different environmental consequences.
Learning Goal 3
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.
Learning Goal 4
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.
Learning Goal 5
Energy from the sun (and the wind and water energy derived from it) is available indefinitely. Because the transfer of energy from these resources is weak and variable, systems are needed to collect and concentrate the energy.
Learning Goal 6
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.
Learning Goal 7
Energy is required for technological processes such as taking apart, putting together, moving around, and communicating.
Learning Goal 8
People have invented ingenious ways of deliberately bringing about energy transformations that are useful to them.
Learning Goal 9
Energy resources are more useful if they are concentrated and easy to transport.
Learning Goal 10
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.
Learning Goal 11
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.
For Grades: 9-12
Learning Goal 1ab
A central factor in technological change has been how hot a fire could be made. The discovery of new fuels, the design of better ovens and furnaces, and the forced delivery of air or pure oxygen have progressively increased the maximum possible temperature.
Learning Goal 1c
Lasers are a new tool for focusing radiation energy with great intensity and control.
Learning Goal 2
When selecting fuels, it is important to consider the relative advantages and disadvantages of each fuel.
Learning Goal 3
Nuclear reactions release energy without the combustion products of burning fuels, but the radioactivity of fuels and their by-products poses other risks.
Learning Goal 4
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.
Learning Goal 5
Decisions to slow the depletion of energy resources can be made at many levels, from personal to national, and they always involve trade-offs involving economic costs and social values.
Learning Goal 6
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.
Learning Goal 7
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.
Learning Goal 8
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.
Subchapter D
Communication
For Grades: K-2
Learning Goal 1
Information can be sent and received in many different ways. Some allow answering back and some do not. Each way has advantages and disadvantages.
Learning Goal 2
Devices can be used to send and receive messages quickly and clearly.
Learning Goal 3
People have always tried to communicate with one another. Signed and spoken language was one of the first inventions.
Learning Goal 4
Early forms of recording messages used markings on materials such as wood or stone.
For Grades: 3-5
Learning Goal 2
Communication involves coding and decoding information. In any language, both the sender and receiver have to know the same code, which means that secret codes can be used to keep communication private.
Learning Goal 3
People have invented devices such as paper and ink, engraved plastic disks, and magnetic tapes for recording information. These devices enable great amounts of information to be stored, retrieved, and sent to other people or places.
Learning Goal 4
Communication technologies make it possible to send and receive information more and more reliably, quickly, and cheaply over long distances.
For Grades: 6-8
Learning Goal 1
Errors can occur in coding, transmitting, or decoding information, and some means of checking for accuracy is needed. Repeating the message is a frequently used method.
Learning Goal 2
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.
For Grades: 9-12
Learning Goal 1
Almost any information can be transformed into electrical signals. A weak electrical signal can be used to shape a stronger one, which can control other signals of light, sound, mechanical devices, or radio waves.
Learning Goal 2a
The quality of communication is determined by the strength of the signal in relation to the noise that tends to obscure it.
Learning Goal 2b
Communication errors can be reduced by boosting and focusing signals, shielding the signal from internal and external noise, and repeating information, but all of these increase costs.
Learning Goal 2c
Digital coding of information (using only 1's and 0's) makes possible more reliable transmission, storing, and processing of information.
Learning Goal 3
As technologies that provide privacy in communication improve, so do those for invading privacy.
Subchapter E
Information Processing
For Grades: K-2
Learning Goal 1
There are different ways to store things so they can easily be found later.
Learning Goal 2
Letters and numbers can be used to put things in a useful order.
For Grades: 3-5
Learning Goal 1
Computers are controlled partly by how they are wired and partly by instructions called programs which are entered in a computer's memory. Some instructions stay permanently in the machine, but most are coded on disks and are transferred into and out of the computer to suit the user.
Learning Goal 2
Computers can be programmed to store, retrieve, and perform operations on information. These operations include mathematical calculations, word processing, diagram drawing, and modeling complex events.
Learning Goal 3
Mistakes can occur when people enter programs or data into a computer. Computers themselves can make errors in information processing because of defects in their hardware or software.
For Grades: 6-8
Learning Goal 1
Most computers use digital codes containing only two symbols, 0 and 1, to perform all operations. Continuously variable signals (analog) must be transformed into digital codes before they can be processed by a computer.
Learning Goal 2
What use can be made of a large collection of information depends upon how it is organized. One of the values of computers is that they are able, on command, to reorganize information in a variety of ways, enabling people to make more and better uses of a collection of information.
Learning Goal 3
Computer control of mechanical systems can be much quicker than human control. In situations where events happen faster than people can react, there is little choice but to rely on computers. Most complex systems still require human oversight, however, to make certain kinds of judgments about the readiness of the parts of the system (including the computers) and the system as a whole to operate properly, to react to unexpected failures, and to evaluate how well the system is serving its intended purposes.
Learning Goal 4
An increasing number of people work at jobs that involve processing or distributing information. Because computers can do these tasks faster and more reliably, they have become standard tools both in the workplace and at home.
For Grades: 9-12
Learning Goal 1
Computer modeling explores the logical consequences of a set of instructions and a set of data. The instructions and data input of a computer model try to represent the real world so the computer can show what would actually happen. In this way, computers assist people in making decisions by simulating the consequences of different possible decisions.
Learning Goal 2
Redundancy can reduce errors in storing or processing information but increases costs.
Learning Goal 3
Miniaturization of information processing hardware can increase processing speed and portability, reduce energy use, and lower cost. Miniaturization is made possible through higher-purity materials and more precise fabrication technology.
Subchapter F
Health Technology
For Grades: K-2
Learning Goal 1a
Vaccinations and other scientific treatments are used to protect people from getting certain diseases.
Learning Goal 1b
Medicines may help those who do become sick to recover.
Learning Goal 2
Tools such as thermometers and X-ray machines are used to help figure out whether a person is healthy.
For Grades: 3-5
Learning Goal 1
There are normal ranges for body measurements—including temperature, heart rate, and what is in the blood or urine—that help to tell when people are well.
Learning Goal 2
Technology has made it possible to repair and replace some body parts.
For Grades: 6-8
Learning Goal 1
Sanitation measures such as the use of sewers, landfills, isolation, and safe food handling are important in controlling the spread of organisms that cause disease. Improving sanitation to prevent disease has contributed more to saving human life than any advance in medical treatment.
Learning Goal 2
The ability to measure the level of substances in body fluids has made it possible for physicians to better diagnose illnesses and monitor the effects of the treatments they prescribe.
Learning Goal 3
It is possible to manufacture complex chemical substances such as insulin and hormones that are normally found in the body. They can be used by individuals whose own bodies do not produce the amounts required for good health.
Learning Goal 4
As the knowledge of how cells in the body detect and fight invaders has grown, the transplantation of tissue or whole organs has become increasingly common. New materials that are durable and less likely to be rejected by the immune system now make it possible to replace some body parts and to implant devices for electrically pacing the heart, sensing internal conditions, or slowly dispensing drugs at optimal times.
Learning Goal 5
Many diseases are caused by bacteria or viruses.
Learning Goal 6
If the body's immune system cannot suppress a bacterial infection, an antibacterial drug may be effective—at least against the types of bacteria it was designed to combat. Less is known about the treatment of viral infections, especially the common cold. However, more recently, useful antiviral drugs have been developed for several major kinds of viral infections, including drugs to fight HIV, the virus that causes AIDS.
Learning Goal 7
Increased knowledge about nutrition has led to the development of diets containing the variety of foods that can help people live longer and healthier lives.
For Grades: 9-12
Learning Goal 1
Owing to the large amount of information that computers can process, they are playing an increasingly larger role in medicine. They are used to analyze data and to keep track of and communicate diagnostic information about individuals and statistical information on the distribution and spread of various maladies in populations.
Learning Goal 2
Almost all body substances and functions have daily or longer cycles. These cycles often need to be taken into account in interpreting normal ranges for body measurements, detecting disease, and planning treatment of illness. Computers aid in detecting, analyzing, and monitoring these cycles.
Learning Goal 3
Knowledge of genetics is opening whole new fields of health care. In diagnosis, mapping of genetic instructions in cells makes it possible to detect defective genes that may lead to poor health. In treatment, substances from genetically engineered organisms may reduce the cost and side effects of replacing missing body chemicals.
Learning Goal 4
Inoculations use weakened germs (or parts of them) to stimulate the body's immune system to react. This reaction prepares the body to fight subsequent invasions by actual germs of that type. Some inoculations last for life.
Learning Goal 5
Knowledge of molecular structure and interactions aids in synthesizing new drugs and predicting their effects.
Learning Goal 6
Techniques for detecting and diagnosing mental disorders include observation of behavior, in-depth interviews, and measurements of brain activity. Treatments for mental disorders range from conversation with the patient to treating the brain with chemicals, electric shock, or surgery.
Learning Goal 7
Biotechnology has contributed to health improvement in many ways, but its cost and application have led to a variety of controversial social and ethical issues.
Learning Goal 8
The incorrect use of any given antibacterial drug can lead, by means of natural selection, to the spread of bacteria that are not affected by it.
Learning Goal 9
Computer controlled devices that emit and detect sound waves, magnetic fields, electromagnetic waves, or nuclear radiation are used to produce still or moving images of the body in two or three dimensions. Devices that involve the same basic technologies as advanced detection equipment, but using higher intensities, provide alternatives to surgery.
