Models and Sources

How do Scientists Use Models

• A model is any representation of an object or process

  • Examples: globes, posters​, sculptures, computer programs

    • Not all models are physical

  • Allow Scientists to test ideas about things they can't observe directly

    • Things that are very small or very large

  • Used to represent Systems

Lesson 2.4 | Grade 8 Science Ohio

Characteristics of Systems

• A system is a group of parts that work together to carry out a function

  • Many things exist as systems

    • bikes, toasters, flashlights

  • All systems have at least one input, one process and one output​

    • Input: a material/energy that goes into a system

    • Process: action or series of actions that happen in a system

    • Output: the material or energy that comes out of the system

      • Feedback: Output that changes a system in someway

        • Example: Your thermostat tells the furnace to heat the house to a certain temperature. Once it hits that temperature, the furnace shuts off

Lesson 2.4 | Grade 8 Science Ohio

How do Models help Scientists understand systems?

• Observing inputs and outputs in a system can be easy, but seeing the processes can be difficult

• Scientists build models to represent a process

  • Test different processes to see if the inputs/outputs of their models match the inputs/outputs in the real world

  • Models can help predict changes in a system

  • Example: The Everglades

    • https://www.smithsonianmag.com/videos/category/science/florida-everglades-restoring-the-wetlands/

Lesson 2.4 | Grade 8 Science Ohio

Modeling Simple & Complex Systems

• Some Systems are simple with only one or two inputs or outputs, but others are much more complex

  • Example: Weather systems

• In order to study complex systems, scientists ofte​n break them down into smaller, more specific parts of the systems

Lesson 2.4 | Grade 8 Science Ohio

​Scientific Models

A simplified representation of a real object or system.

​

• Very large

​​• Very Small

• Very Complex​

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Testing Assumptions

• When a scientist constructs a model of a system, they begin with certain assumptions

  • It is important ​to check those assumptions by comparing the inputs and outputs of the natural world to those in the model

    • if they match, those assumptions are presumed correct

    • if they don't match, scientists must change their assumptions and adjust their models

  • Some assumptions are used to simplify complex models

    • example: Food webs can be simplified to make it easier to study interactions between only two organisms

Lesson 2.4 | Grade 8 Science Ohio

• Notice patterns

• Develop or revise representations • Predict or explain events or relationships

​• Safety

​Benefits

• Very large

​​• Very Small

• Very Complex​

Useful ​

​Scientific Models

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​Reliable vs. Unreliable Sources

• Peer-Reviewed scientific journals

• Encyclopedias

• Nonfiction books written by scientist

• Government websites and publications

​Reliable Sources

​Reliable vs. Unreliable Sources

• Personal websites and blogs

• Online encyclopedias edited by the public

• Books written by nonexperts

• Advertisements

Unreliable Sources

• Peer-Reviewed scientific journals

• Encyclopedias

• Nonfiction books written by scientist

• Government websites and publications

​Reliable Sources