ACTIVITY 2C
Independent and Dependent Variables
There can only be one independent variable and one dependent variable in
an experiment. Everything else that can impact the experiment must be kept
constant or controlled. These are known as “controls”.
What’s an independent variable?
A
n independent variable is exactly what it sounds like. It is
a variable that stands alone and does not respond to other
variables. It causes things to happen! The independent variable is
selected by YOU! The independent variable is also controlled by YOU!
In other words, you can manipulate the independent variable during
an experiment to discover what effect it has on other variables.
THIS IS THE CAUSE!
Activity 2
In fact, experiments are designed to help discover some kind of relationship
between the variables: does the independent variable cause some kind of
change in the dependent variable.
GRANNY ON THE RAMP
Scientists are always conducting experiments using variables. But what is a
variable? In science, a variable is something that is changed or can change.
In experiments, variables are used to help determine “the cause” and “effect”.
Variables come in pairs: independent variables and dependent variables. An
independent variable can be thought of as the “cause” of change. A dependent
variable is what is “effected” by the independent variable.
What’s a dependent variable?
A
dependent variable is exactly what it sounds like. It is
dependent on another variable; specifically, the independent
variable. Usually when you are looking for a relationship between
two things you are trying to find out what makes the dependent
THIS IS THE EFFECT!
Teacher Enrichment Initiatives
2012© The University of Texas Health Science Center at San Antonio
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TEACHER SECTION
STUDENT SECTION
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ACTIVITY 2C
Independent and Dependent Variables
Now that you know about independent variables and
dependent variables, how can you use them to help
write a hypothesis? Remember: when learning to write
a hypothesis, we will start with “if/then” statements. For example:
If something is changed, then it will cause an effect.
Did you notice the words changed and effect? An independent variable
is changed by the scientist and the dependent variable is effected.
In other words, the variables can help you write a hypothesis! The
independent variable should be in the “if” section of the hypothesis.
The dependent variable should be in the “then” section of the
hypothesis.
Your Turn:
A scientist thinks that if she increases the temperature in a room, it
will cause the plants in the room to grow taller. What can the scientist
change? What is effected? With a partner, complete the following:
What is the independent variable?
What is the dependent variable?
Write a hypothesis for the scientist:
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GRANNY ON THE RAMP
Activity 2
Bringing it together:
STUDENT SECTION
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If
,
then
.
Teacher Enrichment Initiatives
2012© The University of Texas Health Science Center at San Antonio
ACTIVITY 2C
Independent and Dependent Variables
Hypothesis: Example A
IV
Constants
DV
Hypothesis: Example B
If I place a raw egg in container with two cups of
water and four tablespoons of salt then the egg
will float.
Complete the following chart for Example B
IV
Constants
DV
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TEACHER SECTION
Teacher Enrichment Initiatives
2012© The University of Texas Health Science Center at San Antonio
Activity 2
Complete the following chart for Example A
GRANNY ON THE RAMP
If I put an ice cube made with tap water in a room
with a temperature of 68 degrees Fahrenheit,
then it will melt in less than 30 minutes.
STUDENT SECTION
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