Identifying Variables
&
Designing
Investigations
GOBSTOPPER VARIABLES
 SIZE






(BIGGER/SMALLER)
CRUSHED
SHAPE
COLOR
BRAND
TEMPERATURE
QUANTITY
WATER
 TYPE (SPRING,




TAP)
TEMPERATURE
AMOUNT
CARBONATED
ADDING ANOTHER
CHEMICAL LIKE AN
ACID OR SOAP
CONTAINER




SIZE
SHAPE
TYPE OF BOTTOM
DIFFERENT
MATERIAL
(SYROFOAM
WOULD INSLUATE
AND IT WOULD
TAKE LONGER)
 DEPTH
3 Kinds of Variables
 Dependent Variable –What is being
tested
 Time it takes for a gobstopper to
dissolve.
3 Kinds of Variables
 Independent Variable –what is being
CHANGED.
 Example: The liquid
3 Kinds of Variables
 Controlled Variable – a variable that
is not changed
 Also called constants
 Controlled variables stay the same in
the investigation
For Example:
Students of different ages
were given the same jigsaw
puzzle to put together.
They were timed to see how
long it took to finish the
puzzle.
Identify the variables in this
investigation.
Re-write as: ________
depends on ____________.
What was the independent
variable?
 The times it takes to complete
the puzzle depends on the age
of the students.
 Ages of the students
(INDEPENDENT VARIABLE)
What was the dependent variable?
 The time it to put the puzzle
together
The time it takes to finish the puzzle
DEPENDS on the age of the students.
What would be the controlled
variable in this example?
 Same puzzle
 All of the participants were
tested with the same puzzle.
 It would not have been a fair
test if some had an easy 30
piece puzzle and some had a
harder 500 piece puzzle.
Another example:
The number of puppies in a
litter is determined by the size
of the mother.
What are the variables in this
investigation?
The number of puppies in a litter
depends on the size of the mother.
Independent variable:
 Size of the mother – what
could be changed
Dependent variable:
 Number of puppies
 The number of puppies
DEPENDS on the size of the
mother.
Controlled variables:
 Type of puppies
 None of these items were changed
One more:
The higher the temperature
of water, the faster an egg
will boil.
The time it takes the egg to
boil depends on the
temperature of the water
 Dependent variable – time to cook
an egg
 Independent variable – temperature
of water
 Controlled variable – type of egg
Last one:
The temperature of
water was measured at
different depths of a
pond.
 Dependent variable – temperature
 Independent variable – depth of the
water
 Controlled variable – thermometer
Designing Investigations
The greater the amount of soap in a
soap and water mixture, the bigger a
soap bubble can be blown.
 Design an investigation to test this
hypothesis.
 Identify the variables
 What exactly will be changed? How
will it be changed?
 What exactly will be measured? How
will it be measured?
The farther a ball drops, the higher
it will bounce.
 Design an investigation to test this
hypothesis.
 Identify the variables
 What exactly will be changed?
How will it be changed?
 What exactly will be measured?
How will it be measured?