NSES Content Standard E Science and Technology: Understandings about science and technology Grades 5-8, page 166 Technological designs have constraints. Some constraints are unavoidable, for example, properties of materials, or effects of weather and friction; other constraints limit choices in the design, for example, environmental protection, human safety, and aesthetics.

 
Benchmark 3B The Nature of Technology: Design and Systems
Grades 6-8, page 51
Design usually requires taking constraints into account. Some constraints, such as gravity or the properties of the materials to be used, are unavoidable. Other constraints, including economic, political, social, ethical, and aesthetic ones, limit choices.

Benchmark 3C The Nature of Technology: Issues in Technology
Grades 3-5, page 54
Scientific laws, engineering principles, properties of materials, and construction techniques must be taken into account in designing engineering solutions to problems. Other factors, such as cost, safety, appearance, environmental impact, and at will happen if the solution fails also must be considered.