1. Models, Scientific and Otherwise, and Theories

2. 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

3. 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?

4. 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.

5. 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.

6. 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

7. 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?

8. 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

9. 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

10. 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

11. Model Success How do scientists evaluate the success of a model?
Can the model explain most or all of past observations?
Can the model be used to predict the happenings of the system or event if it is manipulated in a specific way?
Is the model consistent with other ideas we have about how the world works?
Is it cost effective?