Page 133 - Standards for K-12 Engineering Education

Standards for K-12 Engineering Education?

118 STANDARDS FOR K–12 ENGINEERING EDUCATION?

Table 1. Benchmarks for Science Literacy: Chapter 3B Design and Systems

Grades People can use objects and ways of doing things to solve problems.
K–2
People may not be able to actually make or do everything they design.

Grades There is no perfect design. Designs that are best in one respect (safety or ease of use, for example) may
3–5 be inferior in other ways (cost or appearance). Usually some features must be sacrificed to get others.
How such trade-offs are received depends on which features are emphasized and which are down-played.

Even a good design may fail. Sometimes steps can be taken ahead of time to reduce the likelihood of
failure, but it cannot be truly eliminated.

The solution to one problem may create other problems.

Grades Design usually requires taking constraints into account. Some constraints, such as gravity or the
6–8 properties of the materials to be used, are unavoidable.

Other constraints, including economic, political, social, ethical, and aesthetic ones, limit choices.

All technologies have effects other than those intended by the design, some of which may have been
predictable and some not. In either case, these side effects may turn out to be unacceptable to some of the
population and therefore lead to conflict between groups.

Almost all control systems have inputs, outputs, and feedback. The essence of control is comparing
information about what is happening to what people want to happen and then making appropriate
adjustments. This procedure requires sensing information, processing it, and making changes. In almost
all modern machines, microprocessors serve as centers of performance control.

Systems fail because they have faulty or poorly matched parts, are used in ways that exceed what was
intended by the design, or were poorly designed to begin with. The most common ways to prevent failure
are pretesting parts and procedures, overdesign, and redundancy.

Grades In designing a device or process, thought should be given to how it will be manufactured, operated,
9–12 maintained, replaced, and disposed of and who will sell, operate, and take care of it. The costs associated
with these functions may introduce yet more constraints on the design.

The value of any given technology may be different for different groups of people and at different points
in time.

Complex systems have layers of controls. Some controls operate particular parts of the system and some
control other controls. Even fully automatic systems require human control at some point.

Risk analysis is used to minimize the likelihood of unwanted side effects of a new technology. The public
perception of risk may depend, however, on psychological factors as well as scientific ones.

The more parts and connections a system has, the more ways it can go wrong.

Complex systems usually have components to detect, back up, bypass, or compensate for minor failures.

To reduce the chance of system failure, performance testing is often conducted using small-scale models,
computer simulations, analogous systems, or just the parts of the system thought to be least reliable.

Copyright © National Academy of Sciences. All rights reserved.