Remember...
Independent Variables answer the question...
What do I change?
Dependent Variables answer the question...
What do I observe?
Controlled Variables answer the question...
What do I keep the same?
A scientist is testing the effect of light and dark on
the behavior of moths by turning a light on and off.
What is the Independent variable?
The independent variable is the amount of light and
the moth's reaction is the dependent variable.
A change in the independent variable directly causes a
change in the dependent variable.
The time it takes to run a kilometer depends on
the amount of exercise a person gets.
What is the IV (Independent Variable)?
IV = Amount fo exercise
DV= Time to run a kilometer
The higher the temperature of water, the faster the
egg will cook.
What is the DV(Dependent Variable)?
DV= Time needed for the egg to cook
IV= Temperature of the water
An investigation was done to see if keeping the
ligghts on for different amounts of time each day
affected the number of chicken eggs layed.
What are the two variables?
Variable #1= Hours (amount) of light
Variable #2= Number of eggs
Manipulated Variables
If a variable is deliberately changed in a situation,
it is called a Manipulated Variable
MV=IV
What variable is being manipulated in the
following situations?
The amount of pollution produced by cars was
measured for cars using gasoline containing
different amounts of lead?
Answer: Amount of lead in gasoline
Lemon tress receiving the most water produced
the largest lemons...
Answer: The amount of water.
Responding Variable:
The variable that may change as a result of the
maniplulation is called the responding variable.
RV=DV
Identify the manipulated (IV) variable and the
responding (DV) variable in the following
situations....
More bushel of potatoes will be produced if the
soil is fertilized more...
Answer:
MV: Amount Fertilizer
RV: # of bushels of potatoes
5 groups of rats are fed identical diets except for
the amount of vitamin A that they receive. Each
group gets a different amount. After 3 weeks on
the diet, the rats are weighed to see if their weight
has changed.
What is the MV and RV?
MV= Amount of Vitamin A(IV)
RV= Weight of rats (DV)
Now! Let's put the data from the variables into a
table and learn how to graph the data.
Usually the manipulated variable (IV) is written on
the left, but not laways.
Lenght of Drop
(Cm)
Height of Bounce
(cm)
10
8
50
40
70
56
The Independent Variable is ALWAYS graphed on
the X-axis
The Dependent Variables is ALWAYS graphed on
the Y- axis
D Dependent
R Responding
Y axis
M Manipulated
I Independent
X- Axis