1. Models as Tools in Science
Pearson: Science and Technology - Chapter 3 Lesson 4

2. Flying Through Space
You don’t have to be an astronaut to experience what it’s like to fly in space.
Thanks to technological advances, space flight simulation software programs have been created.
These programs range from simple and straightforward to detailed and complicated.
Depending on which one you use, you can experience what it might feel like to fly to the moon, command a mission to Mars, and even explore other solar systems.
If you’ve ever wondered what it’s like to be an astronaut, now you have the chance to find out!

3. Flying Through Space
Why would a flight simulation software program created today be more realistic than one that was created ten years ago?
Would you be able to really fly in space if you knew how to use a space flight simulation software program? Explain.

4. Why Do Scientists Use Models?
In science, a model is any representation of an object or process.
Pictures, diagrams, computer programs, and mathematical equations are all examples of scientific models.
Scientists use models to understand things they cannot observe directly.
They make physical models to represent things that are either very large, such as Earth’s core, or very small, such as an atom.
Other models, such as mathematical equations or word descriptions, are models of processes.

5. Why Do Scientists Use Models?
How do models help scientists?

6. How Are Models of Systems Used?
It’s easy to identify the inputs and outputs of a system. It’s not so easy to observe a system’s process.
Scientists use models to understand how systems work.
They also use models to predict changes in a system as a result of feedback or input changes.
However, they keep in mind that predictions based on models are uncertain.

7. How Are Models of Systems Used?
When scientists construct a model of a system, they begin with certain assumptions.
These assumptions allow them to make a basic model that accurately reflects the parts of the system and their relationships. 
A food chain is a good model of a simple system to begin to understand how energy moves through living things in an environment.
However, it shows how only a few of those living things are related.
So a scientist may build a food web to model a more complete picture of the system.

8. How Are Models of Systems Used?
Some systems that scientists study are complex.
Many parts and many variables interact in these systems.
So scientists may use a computer to keep track of all the variables.
Because such systems are difficult to model, scientists may model only the specific parts of the system they want to study.
Their model may be used to show the processes in the system or to make predictions.

9. How Are Models of Systems Used?
Why do scientists use models of systems?

10. What Is a System?
A system is a group of parts that work together to perform a function or produce a result.
All systems have input, process, and output.
Input is the material or energy that goes into a system.
Process is what happens in a system.
Output is the material or energy that comes out of a system.
Some systems also have feedback, output that changes the system in some way.

11. What Is a System?
Describe three components of a system.

12. Modeling a System Scientists use models to study systems.
Systems are groups of parts that work together to perform a function or produce a result.
Models leave out certain variables, particularly aspects that can't be observed.
This makes complex systems easier to understand.
All systems have four basic elements: input, process, output, and feedback. Input is incoming material or energy.
Process is what happens in a system.
Output is the outgoing material or energy.
Feedback is output that changes the system.

13. Modeling a System
Food chains and food webs are very common systems in nature, and can be easier to understand using models.
Here's a model of a simple food chain in the Florida Everglades, showing one pathway along which energy moves through the system.
Input: Algae, which are simple plants, make food using the sun's energy.
Process: Flagfish eat the algae.
Output: The flagfish have energy to grow, swim, live, and reproduce.
The flagfish become an input for animals higher on the food chain, such as the largemouth bass, which in turn becomes input for fish-eating birds.

14. Modeling a System
Imagine a tree leans over the water's edge, blocking sunlight.
A lack of sunlight prevents the growth of algae, which reduces the food supply for flagfish.
With less food available, the population of flagfish decreases.
Then a storm blows the tree over.
More sunlight allows the algae population to increase.
More food becomes available for flagfish.
This increased food supply allows the reproduction of flagfish to increase.
The change in flagfish population is the output of the system.
The change in algae population is feedback that affects the output of the system.

15. Modeling a System
Systems such as food chains can be modeled using diagrams. Other systems, including electrical circuits, can also be modeled using diagrams.

16. Modeling a System
Think of another system and describe how you would model it. Be sure to include the four parts of a system: input, process, output, and feedback.

17. Sea Breezes
Sun, air, land, and water are the parts of a system that produce a sea breeze.
During the day, the sun's energy heats both the land and the water.
The land and water, in turn, heat the air above them.
Air over the land becomes much warmer than the air over water.
As the warmer air rises, the cooler air from over the water rushes in to replace it.
A sea breeze is the result.

18. Sea Breezes
Identify Identify the input, output, and process of the sea breeze system.
Challenge Which parts of this system will change after the sun sets? How will it change?

19. Key Concept Summaries Why do Scientists Use Models?
In science, a model is any representation of an object or process. Pictures, diagrams, computer programs, and mathematical equations are all examples of scientific methods. Scientists use models to understand things they cannot observe directly.
They use models as representations of things that are either very large, such as Earth’s core, or very small, such as an atom. These are physical models. Other models, such as mathematical equations or world descriptions, are models of processes.

20. Key Concept Summaries What is a System?
A system is a group of parts that work together to perform a function or produce a result.
All systems have input, process, and output.
Input is the material or energy that goes into a system.
Process is what happens in a system.
Output is the material or energy that comes out of a system.
Some systems also have feedback, output that changes the system in some way.

21. Key Concept Summaries How Are Models of Systems Used?
It’s easy to identify the inputs and outputs of a system. It’s not so easy to observe a system’s process.
Scientists use models to understand how systems work.
They also use models to predict changes in a system as a result of feedback or input changes.
However, they keep in mind that predictions based on models are uncertain.
When scientists construct a model of a system, they begin with certain assumptions.
These assumptions allow them to make a basic model that accurately reflect the parts of the system and their relationships.
A food chain is a good model of a simple system to begin to understand how energy moves through living things in an environment.
However, it shows how only a few of those things are related.
So a scientist may build a food web to model a more complete picture of the system.

22. Key Concept Summaries Some systems that scientists study are complex.
Many parts and many variables interact in these systems.
So scientists may use a computer to keep track of all the variables.
Because such systems are difficult to model, scientists may model only the specific parts of the system they want to study.
Their model may be used to show the processes in the system or to make predictions.