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Dependent Variables in Experiments
 Used with the scientific method
Scientific Method
(In List Format)
Step 1: Ask A Question
Step 2: Form A Hypothesis
Step 3: Test The Hypothesis
Step 4: Analyze The Results
Step 5: Draw Conclusions
Step 6: Communicate Results
Step 7: Make Observations
 Use dependent variables when you test your hypothesis by doing
experiments
1
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2 Types of Variables
Independent & Dependent
In an experiment…
 …you should only test for ONE key thing at a time
When you repeat the experiment…
 …only change this ONE key thing
This one thing is called…
ANYTHING ELSE THAT CHANGES IS CALLED…
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So What Is A Dependent Variable?

Other factors that change because of the independent variable

These are the things that YOU DO NOT CHANGE…they
change on their own

In other words, anything that changes on its own will be a…
Imagine you are doing an experiment to determine which brand
of gum will have flavor that lasts the longest.

The one thing you will change each time is the brand of gum

So the independent variable is the brand of gum

How long the flavor lasts will change on its own

So the dependent variable is how long the flavor lasts
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Example 01 You decide to do an experiment to determine the reason
certain soft drinks are more popular that other soft drinks. You
suspect that the popularity of the drinks is connected with the
amount of sugar found in them. You decide to use Coke, Pepsi, and
Dr. Pepper in this experiment. You first determine how much sugar
each drink contains. Then you get 6 students to do a blind taste test
with all 3 drinks. They rate each drink on a scale of 1 to 10.
The independent variable is…the type of soft drink
So what is the dependent variable?
HINT: What is a factor that changed without you doing it?
The dependent variable is the student’s rating
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Example 02: A scientist is conducting an experiment to test how
sunlight affects plant growth.
 She places one corn plant 1 meter away from a sunlamp.
 She places one corn plant 2 meters away from a sunlamp.
 She places one corn plant 3 meters away from a sunlamp.
The independent variable is…the amount of sunlight
So what is the dependent variable?
HINT: What is a factor that changed without you doing it?
The dependent variable is the plant growth
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Example 03: A student conducts an experiment with ten 8th grade
students (5 boys and 5 girls). He uses 3 similar types of sour candy
(Sour Skittles, Sour Patch Kids, and Warheads) in a series of 4
trials. He gives 1 piece of candy to each student and records their
facial expressions as they eat it.
The independent variable is…the type of sour candy
So what is the dependent variable?
HINT: What is a factor that changed without you doing it?
The dependent variable is the student’s facial reactions
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Example 04: A student conducts an experiment to determine
which type of glue works best for attaching two pieces of regular
writing paper together.
He uses 3 types of Elmer’s glue in a series of experiments
(1) Liquid-washable, (2) Glue Stick-washable, (3) Glue Stick-nonwashable)
He places the same amount of glue (2g) on each sheet of paper.
The independent variable is…the type of glue
So what is the dependent variable?
HINT: What is a factor that changed without you doing it?
The dependent variable is how strongly
the sheets of paper stick together
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Example 05: A student conducts an experiment to determine which
ink color in ballpoint pens will last the longest before running out.
She uses 3 ink colors in 3 ballpoint pens in a series of experiments.
(1) Black ink pen, (2) Blue ink pen, (3) Red ink pen)
She copies text from his science book. She copies the same text over
and over. She writes at the same speed. The room temperature
remains the same. She writes on the same kind of paper.
The independent variable is…the ink color
So what is the dependent variable?
HINT: What is a factor that changed without you doing it?
The dependent variable is how long ink lasted
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