Transcript Independent Variable

1) Problem Statement:
Select a topic that can only be answered by
experimenting.
The problem statement is always is written as a
question.
Hint: It is good for the question to start with
“which amount” or “how will?”
When creating your problem
statement for your experiment, you
need be able to measure your results
in some way.
You also need to make sure that your
question is clear and specific enough
to do an experiment.
Formula for a good Problem
Statement:
–How will the independent variable
affect the dependent variable?
Example Problem Statements:
• How will the height of a ramp affect the distance
that a car will travel?
• Which amount of salt dissolved in water will
freeze in the shortest period of time?
In a problem statement, you want to
ask how your independent variable
will affect your dependent variable.
• What is a variable?
Variables: the factors that affect your
investigation
• Independent Variable: What the experimenter
changes on purpose in his or her experiment
– (ex. You change the height of the car ramp)
• Dependent Variable: the response that is
measured (it DEPENDS on the independent
variable in order to change) (ex. The distance
that the car travels)
If our problem statement is “How will
the amount of salt affect how quickly
water freezes?”
• What is the independent variable?
• What is the dependent variable?
“How will the amount of salt affect
how quickly water freezes?
• Independent Variable: amount of salt
• Dependent Variable: the time water takes to
freeze
What are Constants in an experiment?
Constants = the parts of the
experiment that stay the same
In order to ensure that you are actually
testing the effects of the amount of salt
added, you need to make sure that other
variables are not changing the results
• What are other variables in this experiment
that could change the results if we do not
keep them constant?
Other variables in the experiment:
• Water temperature
• Amount of water
• Freezer temperature
– We need to keep all of these variables constant
Example: Hypothesis: I think that the ice cube with the least
amount of salt will freeze in the shortest period of time.
• Independent variable: the amount of salt that
I add (that is the only thing I am changing)
• Dependent variable: the period of time that it
takes to freeze
• Constants: the amount of water that I add,
the temperature of the freezer
Constants: the parts of the
experiment that you keep the same
Try to keep all parts of your
experiment the same beside the
independent variable (what you are
intentionally trying to change)
For example, what would happen if
you did the freezing experiment with
different sized glasses?
Answer: You would not just be testing
to see how the amount of salt affects
the time it takes water to freeze,
because other variables are involved.
The glass with the larger amount of
water will probably take more time to
freeze
Constants: Keeps everything about the
experiment the same, so that only the
independent variable is influencing the
dependent variable