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Models, Scientific
and Otherwise,
and Theories
Can you name some models?
• Model cars
• Model of the globe
• Model of the solar system (orrery)
• Model of the human skeleton
• Model of the skin
• Model of the brain
• Model of Earth’s crust
How do we use these models?
• Learn the parts of a whole
• Help us visualize something very large, very small, and/or
complex
• Help us visualize hidden (internal) structures
• Help us visualize relationships among parts
• For explanation and teaching
Are scientific models different from these types of
models?
Scientific models
• When the data support a hypothesis, scientists usually try to
explain the phenomena or system they are studying by
constructing a model.
• A model in science is more than a physical object or mental
picture; it is an explanation of how phenomena occur (a
mechanism) and how data or events are related. It is a
representation of a system or phenomenon. It is dynamic,
not static.
• It can be visual, verbal, or mathematical.
Why Use Scientific Models?
• Do scientists use models in the same way? They can, for
basic explanation and description (skin, brain, globe), but
they more often use models that can be modified as their
understanding of a system or phenomenon grows, through
the practices of (1) designing experiments, (2) collecting
data, (3) analyzing their results, (4) discussing and
interpreting evidence, and (5) communicating their findings
to others.
Scientists Using Models
Scientists typically use models to
• Study extremely complex systems, for example, Earth’s
climate which has many factors that are dependent on one
another. Such a system is impossible for scientists to work
with as a whole.
• Study extremely small or extremely large systems
• Make predictions
• Compare outcomes among competing models
• Test out ideas that would be impractical (too expensive, too
large) or impossible (inaccessible, back in time) otherwise
Models and Theories
• If a model is very successful at explaining
many phenomena, it may become part of a
theory, a broad generalization that explains a
body of facts or phenomena.
• Can you think of some models that have
become theories?
Benefits of Using Models
• Allow us to test, evaluate, and revise as much as we need
• Can be much simpler than the system or phenomenon being
studied
• Can be manipulated and adjusted far more easily than a real
system.
• Can allow us to ‘slow down’ a process so we can better
understand what is happening.
• Can show how a system changes over time, extending our
knowledge into the future (predictions).
• Can allow for safe testing of an idea or event under controlled
circumstances
• Can be far cheaper than running actual tests
Drawbacks of Using Models
• Can be overly simplified to the point of not being very useful
• Often leave out important aspects or factors so that results
aren’t realistic
• Are always less reliable than direct measurements would be
Types of Models
• Physical replicas that are 3-D representations (brain, skin layers,
toy car)
• Conceptual: Drawings or diagrams that represent one’s current
conceptual understanding about how a specific natural system
behaves (atomic theory, plate tectonics)
• Mathematical Equations (electricity and magnetism, relativity)
• Computer simulations (formation of the moon, asteroid impact)
• Flow charts (business models)
• Graphs
Model Success
How do scientists evaluate the success of a model?
1) Can the model explain most or all of past observations?
2) Can the model be used to predict the happenings of the system or
event if it is manipulated in a specific way?
3) Is the model consistent with other ideas we have about how the
world works?
4) Is it cost effective?