Answers: Identifying Variables and Controls
Scenario #1: Music may help people relax. Darius got two groups of people together.
He took everybody’s pulse and blood pressure. Then he allowed one group to listen to
soothing music while the other group sat in silence. After the song was over, he
measured everyone’s pulse and blood pressure again.
Parts of the Experiment- ANSWERS
Independent variable
Type of music
Dependent variable
Pulse and blood pressure
Experimental control
The group without music
Constants (Factors
monitored to prevent
introducing another
independent variable)
● the instrument used to measure blood pressure
● instrument used to measure pulse
● age/gender of the two groups
Scenario #2: Preservatives such as salt help keep food fresh. Imaan made 18 loaves of
bread using the same recipe and baking method. In nine of them, she used no salt. In
the other nine, she used salt. After the loaves were baked, she placed each of the
loaves in a plastic bag and left them close together on the counter in her kitchen. Each
day she looked at them to see if any mold had started to grow.
Parts of the Experiment- ANSWERS
Independent variable
Amount of salt used in bread
Dependent variable
Mold growth on the bread in the bags
Experimental control
The loaves with no salt
Constants (Factors
monitored to prevent
introducing another
independent variable)
●
●
●
●
●
same recipe
same baking method
number of loaves
location of bread on the counter
type of bags used
Adopted from The Great Fakesperiment by Lisa Schunk NSTA Science Scope January 29,
2009, Vol 32: Issue 06 p. 2
Scenario #3: Emily made four paper helicopters. Each was made out of a different kind
of paper. She flew each one several times in the hallway and recorded how long each
stayed in the air. What is the experimental variable?
Parts of the Experiment- ANSWERS
Independent variable
Type of paper
Dependent variable
Flight time
Experimental control
This investigation does not have an experimental control.
For this investigation, it is not possible to make the
helicopter without the paper.
Constants (Factors
monitored to prevent
introducing another
independent variable)
● Hallway
● Style of helicopter
● Number of times helicopter flown
Scenario #4: Ethan filled 10 cups of the same size with equal amounts of water. He
divided the cups into five groups of two cups each. The groups were placed in five
different locations around his house. After two weeks, he measured the remaining water
to determine how much had evaporated, by measuring how much water remained in
each cup.
Parts of the Experiment- ANSWERS
Independent variable
Location of cups
Dependent variable
Amount of evaporation
Experimental control
There is no experimental control in this investigation.
Constants (Factors
monitored to prevent
introducing another
independent variable)
●
●
●
●
Same size cup
Same amount of water
Amount of time left in locations
(2) cups in each group
Adopted from The Great Fakesperiment by Lisa Schunk NSTA Science Scope January 29,
2009, Vol 32: Issue 06 p. 2