1. What is a Variable?

2. DEFINITION
Variable – Any factor that can change in a scientific investigation or experiment

3. Types of Variables Independent Variable
(also called the manipulated variable)
The condition that is intentionally changed by the investigator in an experiment
There can be only one independent variable in an experiment

4. Types of Variables
Dependent Variable
(also called the responding variable)
The factors or conditions that will change as a result of the independent variable
The factors that you measure or observe as data
There can be one or more dependent variables in an experiment

5. Types of Variables Controlled Variables
The factors or conditions that are kept the same (unchanged) in an experiment.
There are many controlled variables in an experiment

6. Identify variables for the following experiments.
Practice
Identify variables for the following experiments.
You can do it!

7. Testable Question #1
Does changing the temperature of a ball affect the height the ball will bounce?
Cold
Hot

8. Identify Variables #1 Manipulated Variable
Does changing the temperature of a ball affect the height the ball will bounce?
Cold
Hot
Responding Variable

9. Identify Variables #1 Controlled Variables: * Same ball
* Dropped from the same height
* Dropped onto the same surface
* etc…

10. Testable Question #2
Does changing the color of light affect the growth rate of plants?

11. Identify Variables #2 Manipulated Variable
Does changing the color of light affect the growth rate of plants?
Manipulated Variable
Responding Variable

12. Identify Variables #2 Controlled Variables:
* Same type / size of plant
* Same wattage of bulb
* Same amount of water
* Same soil
* Light on for the same amount of
time
* etc…

13. Testable Question #3
How does the size of a parachute affect the time it takes a
hippo to fall 10 feet?

14. Identify Variables #3 Manipulated Variable
How does the size of a parachute affect the time it takes a hippo to fall 10 feet?
Manipulated Variable
Responding Variable

15. Identify Variables #3 Controlled Variables: * Same hippo
* Dropped from the same height
* Same parachute fabric
* Same length of strings on the parachute
* etc…

16. Simpsons Controls and Variables
Smithers thinks that a special juice will increase the productivity of workers. He creates two groups of 50 workers each and assigns each group the same task (in this case, they're supposed to staple a set of papers). Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, Smithers counts how many stacks of papers each group has made. Group A made 1,587 stacks, Group B made 2,113 stacks.

17. Identify the… Control Group Experimental Group
Group B: No Juice
Experimental Group
Group A: Drinking Juice
Manipulated (Independent ) Variable
Special Juice
Responding (Dependent ) Variable
Number of Stacks of Paper
Hypothesis:
If the workers drink the special juice,
then the number of stacks of paper will increase.
What should Smithers' conclusion be?
Smithers’ hypothesis is not correct because Group A made , 587 stacks of paper and Group B made 2,113 stacks of paper.
This shows that the juice did not increase the number of stacks of paper, but decreased.