Name: _____________________________
Variables in Science
Science is a process used to learn about the world. In fact, all sorts of
people in all sorts of situations “do science” in everyday life, sometimes
without even realizing that they are acting like scientists. An important part of
science is observing and measuring the things you are investigating.
Sometimes, the value of something—the number you get when you measure
it—can change. A variable is something whose value can change. Often, the
value of a variable is unknown (think x and y in math). The “height of a RHS
student” is a variable. Some students are tall, some are short, and some are in
the middle. The value of the “height of a RHS student” can change, depending
on which student you measure, or when you measure them.
Scientists LOVE variables! Scientists are especially interested in
variables that have some sort of connection or are “in a relationship.” When
two variables are “in a relationship,” one of the variables is called the
independent variable and the other is called the dependent variable. What
is the difference between the independent variable and the dependent
variable? Let’s look at an example.
The distance a soccer ball travels after it is kicked depends on how hard
the ball is kicked. There are two variables in this example. One variable is how
hard the ball is kicked, and the second variable is the distance the ball travels.
Remember, these things are variables because their value can change. The
person doing the kicking decides how hard she wants to kick the ball. How
hard the ball is kicked does not depend directly on some other factor: it is
independent of other influences. Variables that don’t directly depend on other
variables are called independent variables. In this example, how hard the ball
is kicked is the independent variable.
The value of a dependent variable changes when the independent
variable changes. In other words, its value depends on the independent
variable. The distance the ball travels depends on how hard the ball is kicked.
So, distance is the dependent variable in this example. This can also be
Supporting Target A: I can describe what the word variable means, to a scientist
Supporting Target B: I can distinguish between an independent variable and a dependent variable
Name: _____________________________
understood in terms of cause and effect, which is a VERY big thing in science.
A change in the independent variable is a cause. A cause results in an effect:
a change in the dependent variable! In other words: if you kick the ball harder,
it will go farther!
Understanding the relationship between variables is an important part of
science. When two variables have a relationship, changing the value of one
variable has an effect on the value of a second variable. Why does this
matter? Because scientists aren’t just interested in WHAT is happening in the
world, they are interested in finding out WHY things are happening. Studying
the relationships between variables helps scientists figure out why things in the
world change. And, even better, understanding relationships between
variables helps scientists make predictions about what might happen in the
future. Its like magic, but better, because it works!
Supporting Target A: I can describe what the word variable means, to a scientist
Supporting Target B: I can distinguish between an independent variable and a dependent variable