Constant or Controlled Variables 8 th 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 foodenvironment –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? –A–Amount of food –T–Type of chicken –S–Size of chicken --Temperature --Age of chicken environment –A–Amount of water--nesting materials –H–Health of chicken