Science Buddies: "Ask an Expert"

Is it possible to have two variables!?!?!?!

hi lightning699 ,

Welcome to science buddies!

You have an excellent question. A scientific experiment can have only one variable that changes; this is call the independent variable. All other conditions should be the same as much as possible. The result of your experiment, which ideally should be something that you can measure, is called the dependent variable.

https://www.sciencebuddies.org/science- ... bles.shtml

If you have two experimental conditions that you want to test, you will need to set up two experiments, but only one experiment is required for a science project.

I hope this helps. What topic are you investigating?


Donna Hardy

Hi, lightning699!

To add to Ms. Hardy's response, it is possible for you to test two variables in your experiment if you test them separately. In other words, if you wanted to test the effect of two different things (two independent variables) on something (your dependent variable), then you must only manipulate one of them at a time. When one of the variables is beings changed, you must not alter the other one. In that case, whatever variable is not being changed will serve as a control in that trial.

For example, if you wanted to test the effects of light and fertilizer on the growth of a plant, then you would need separate sets of pots. One group would test light exposure and one would test the effects of different amounts of fertilizer. You would record the same data (dependent variable) for both sets—the height of the plant. However, you would never, say, also change the light exposure in a group where you were manipulating the amount of fertilizer. Does this make sense?

Trystan Loustau