NSES Content Standard E  Science and Technology: Understandings about science and technology Grades 5-8, page 166 Perfectly designed solutions do not exist. All technological solutions have trade-offs, 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.

 
Benchmark 3B The Nature of Technology: Design and Systems
Grades 3-5, page 49
There is no perfect design. Designs that are best in one respect (safety or ease of use, for example) may be inferior in other ways (cost or appearance). Usually some features must be sacrificed to get others. How such trade-offs are received depends upon which features are emphasized and which are down-played.

Benchmark 3B The Nature of Technology: Design and Systems
Grades 3-5, page 50
Even a good design may fail. Sometimes steps can be taken ahead of time to reduce the likelihood of failure, but it cannot be entirely eliminated.

Benchmark 3B The Nature of Technology: Design and Systems
Grades 6-8, page 51
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.

Benchmark 3B The Nature of Technology: Design and Systems
Grades 9-12, page 52
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.

Benchmark 3C The Nature of Technology: Issues in Technology
Grades 6-8, page 56
New technologies increase some risks and decrease others. Some of the same technologies that have improved the length and quality of life for many people have also brought new risks.