Did you know science has its own language? Variables play a very important role in scientific experiments. In this lesson, learn what variables are, the different types of variables, and how they interact.
Think Like a Scientist
Which flavor of ice cream will melt fastest: chocolate, vanilla, or strawberry? To answer this question, you have to think like a scientist and set up an experiment.
What would the experiment look like? You could place one scoop of each ice cream flavor in a glass bowl and, using a stopwatch or timer, record how long it takes each scoop to melt.This experiment has a few variables, or characteristics or conditions, that can exist in different amounts or kinds. For example, characteristics like a person’s eye color or hair color come in different kinds, so these could be variables. The temperature outside or in a room is a condition that varies, so it too could be a variable. It is easy to remember what variables are because the beginning of the word ‘variable’ sounds like the word ‘vary,’ which means to change!
Types of Variables
There are three main types of variables: independent, dependent, and controlled. Let’s learn about each one.
The independent variable is the factor that the scientist changes. What was different about the ice cream in our experiment? The flavor. You, the scientist, changed which flavor was put in each bowl.
Independent variables stand alone because they are not influenced, or changed, by anything else in an experiment.
The dependent variable is what is being measured in an experiment. It’s called ‘dependent’ because it depends on the independent variable.In our experiment, we measured how long it took each scoop of ice cream to melt. In this experiment, the time it takes a scoop to melt is dependent on the flavor of the ice cream.
In an experiment, the only thing that should be changing is the independent variable. All other variables have to be the same.
Controlled variables are all the other variables that a scientist must make sure are the same throughout the entire experiment.Our experiment was all about different ice cream flavors – our independent variable. We wanted to know how the flavors affected the melting time. So, other than the experimenter changing the flavors, everything else must stay constant.In our experiment, what else could be different about the conditions of the scoops besides their flavor? You could put two scoops of chocolate ice cream in a bowl but use only one scoop of the other flavors. One bowl could be placed in the sun and the others in the shade. You could even put the scoops in different types of bowls.
If any of these conditions were not exactly the same for each ice cream flavor, when you measure how long it takes the scoops to melt, you could not be certain that flavor was the only reason some scoops melted faster than others.So, you have to control all of the variables in an experiment (except for the independent variable). Only when you are certain that all variables are the same can you know that the results of your experiment are accurate.
Variables are characteristics or conditions that exist in different amounts or types and can be changed in an experiment.
There are three types of variables: independent, dependent, and controlled. Controlling all of the variables in an experiment, except for the independent variable, is the only way to know that the results of an experiment are accurate.