| NSES Content Standard Unifying Concepts
and Processes:
Systems, order, and organization Grades K-12, page 116 The natural and designed world is complex; it is too large and complicated
to investigate and comprehend all at once. Scientists and students learn
to define small portions for the convenience of investigation. The units
of investigations can be referred to as "systems." 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.
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Benchmark 11A Common Themes: Systems
Grades 6-8, page 265
A system can include processes as well as things.
Benchmark 11A Common Themes: Systems
Grades 6-8, page 265
Thinking about things as systems means looking for how every part relates
to others. The output from one part of a system (which can include material,
energy, or information) can become the input to other parts. Such feedback
can serve to control what goes on in the system as a whole.
Benchmark 11A Common Themes: Systems
Grades 9-12, page 266
A system usually has some properties that are different from those
of its parts, but appear because of the interaction of those parts.
Benchmark 11A Common Themes: Systems
Grades 9-12, page 266
Understanding how things work and designing solutions to problems of
almost any kind can be facilitated by systems analysis. In defining a system,
it is important to specify its boundaries and subsystems, indicate its
relation to other systems, and identify what its input and its output are
expected to be.
Benchmark 11A Common Themes: Systems
Grades 9-12, page 266
The successful operation of a designed system usually involves feedback.
The feedback of output from some parts of a system to input for other parts
can be used to encourage what is going on in a system, discourage it, or
reduce its discrepancy from some desired value. The stability of a system
can be greater when it includes appropriate feedback mechanisms.
See also Chapter 11 Common Themes, Section A: Systems for precursor ideas.
Science for All Americans Common Themes
Chapter 11, page 166
Any collection of things that have some influence on one another can
be thought of as a system. The things can be almost anything, including
objects, organisms, machines, processes, ideas, numbers, or organizations.
Thinking of a collection of things as a system draws our attention to what
needs to be included among the parts to make sense of it, to how its parts
interact with one another, and to how the system as a whole relates to
other systems. Thinking in terms of systems implies that each part is fully
understandable only in relation to the rest of the system.
In defining a system whether an ecosystem or a solar system, an educational or a monetary system, a physiological or a weather system we must include enough parts so that their relationship to one another makes some kind of sense. And what makes sense depends on what our purpose is. For example, if we were interested in the energy flow in a forest ecosystem, we would have to include solar input and the decomposition of dead organisms; however, if we were interested only in predator/prey relationships, those could be ignored. If we were interested only in a very rough explanation of the earth's tides, we could neglect all other bodies in the universe except the earth and the moon; however, a more accurate account would require that we also consider the sun as part of the system.