Variables in Science Experiments

Wheat sown at two differnt times being compared to determine which yields a better crop. Photo courtesy of CIMMYT/Flikr. 

When you are testing your hypothesis during the experiment stage of the scientific method, it is important to have only 1 variable that you are testing. A variable is the factor that changes in an experiment.  For example, if you were conducting an experiment to determine how the speed of wind affects the height of waves in the ocean, what would be the variable? What would you change in that experiment? Hopefully you can see that the speed of the wind would be a variable -- that is the thing you are changing.  

However, you may have been confused because there are actually 2 things that can change in this experiment: wind speed and wave height. One of these is the independent variable and the other is the dependent variable. An independent variable is the factor that is being manipulated by the experimenter in an experiment. The dependent variable is the factor that changes as a result of changing the independent variable. In this example, the wind speed is the independent variable and the wave height is the dependent variable. It is very important to have only one independent variable in an experiment. 


Last modified: Thursday, 20 April 2017, 5:50 PM