Science 7
Notes 3
Independant Variable
Dependent Variable
Controlled Variable
Test Group
Control Group
Know how to
identify the
independent and
dependent
variables in a
hypothesis.
Identify the dependent
variable, the
independent variable
and at least three
controlled variables in
an experiment
Steps for Designing a Controlled Experiment
Hypothesis: If I dunk the gummy bear in plain water, then it
will grow larger.
Define
independent
variable.
1. Identify the variables
Independent variable: the SINGLE factor changed in the experiment
o Ex: salt or no salt
Define dependent
variable.
Define controlled
variable.
Explain how
sample size
makes the results
of your
experiment more
valid.
Dependent Variable: the factor being measured
o Ex: gummy bear mass
Controlled variables: all other factors that remain the same
 Ex: amount of water, type and amount of soil, type of plant,
temperature, location....
2. Determine your sample size
The larger the sample size the more valid the results will be!!!!
3. Divide the samples into two (or more) groups
Explain why you
need two groups
in a controlled
experiment.
• Test group: receives the manipulated variable
• Control group: does not receive the manipulated variable
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Science 7
Notes 3
Class Work:
1. What effect does the amount of water have on plant growth?
Hypothesis:_________________________________________________________________
_____________________________________
(IV) Manipulated Variable __________________________________
(DV) Dependent Variable___________________________________
2. Does vitamin C help prevent colds?
Hypothesis:_________________________________________________________________
_____________________________________
(IV) Manipulated Variable __________________________________
(DV) Dependent Variable___________________________________
3. Do cell phones cause cancer?
Hypothesis:_________________________________________________________________
_____________________________________
(IV) Manipulated Variable __________________________________
(DV) Dependent Variable___________________________________
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