Variables in Science

What is the difference between the manipulated variable and the responding variable

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Manipulated Variable   =  What you CHANGED 

(also called the independent variable)

Examples:   played music to a plant

                          caffeine added to fish’s water

                         gave vitamins to a baby cow

Responding Variable  =  What you MEASURED

(also called the dependent variable)

Examples:    how many tomatoes

                           heart rate of fish

                          weight of the cow


Underline the Manipulated variable.  Highlight the Responding variable:

1. You spray mosquito repellant on one arm and count how many mosquito bites you have.

2. A mouse is given a drug and then runs a maze.  The time it takes to complete the maze is compared to the time it took for it to complete the maze without the drug. 

3.  You place different colored liquids in a hummingbird feeder and count how many hummingbirds visit.

4. You give one plant fertilizer and compare how tall it grows to a plant that has not been fertilized.

5.  Listening to crickets, you count how many chirps you can hear at different temperatures.

6.  You place two fish in different sized tanks, after a month, you measure the length of each fish.

Related Resources

Variables with Simpsons – read stories involving characters from the Simpsons and determine the independent and dependent variables

Independent Variables – read a short sentence of science experiment and determine the variables

Beriberi and Penicillin – a short story on the discovery of penicillin and that Beriberi was caused by a vitamin deficiency