Transcript Amount of food Type of chicken

Constant or Controlled
Variables
8th Grade Science
What is a Constant
Variable?
• A constant variable is also called a
Controlled variable. (or Extraneous
variable)
• It is the parts of the experiment that have
to be kept the same so the experiment is a
fair test of the IV.
List the MOST important ones.
• There can be several variables that need
to be controlled or kept the same in the
experiment.
• To save time and space, just focus on the
3 variables that would have THE MOST
INFLUENCE on the outcome of the
experiment.
Where do you find it?
• Listing constant
variables
requires you to
use your prior
knowledge
about the
subject.
Target Practice
• Think of the constant variables in #1 on
your worksheet:
• Does how fast a rose bush
grows depend on the
amount of sunlight it
receives?
MOST influential variable
• Eliminate the IV (sunlight)!!!
• Look for OTHER things
BESIDES the Independent
variable that would influence
the outcome (DV) of the
experiment.
• Use your PRIOR knowledge
about what a plant needs to
grow.
Think…What causes
bacteria to thrive?
• #2 Do bacteria
reproduce at a
faster rate if the
temperature is
warmer?
Got Bacteria??
List the Constant
Variables:
•Amount of moisture
•Amount of light
•nutrients
Try #3 on Your own
• What are all of the variables you have
listed?
– Amount of food ─environment
– Type of chicken ─nesting materials
– Size of chicken
– Age of chicken
– Amount of water
– Temperature
Try #3 on Your own
• What are the most important?
– Amount of food
– Type of chicken
– Size of chicken
--Temperature
--Age of chicken
─environment
– Amount of water --nesting materials
– Health of chicken