vary

Variables come from the word vary which means change.

Variable can have different meanings. When used as an adjective, variable describes something that changes a lot.

For example:

The depth of lake is variable - in some places it is only 2 meters deep. In other places, the lake is up to 40 meters deep.

Variables are factors that researchers measure to see how they change under specific conditions.

Imagine that you buy two plants that are exactly the same. You don’t know how much water to give these plants, so you conduct a small experiment. Once a week, you give one plant a lot of water, and you give the other plant only a small amount of water. One plant grows very fast and the other plant does not grow.

Variables are factors that researchers observe in a research study. They observe and measure these factors in order to see how they change - increase or decrease - under specific conditions.

Researchers wanted to see which variables reduce students' concentration in class.

First they asked a class of students how many hours they sleep at night. Then they asked students if they find it hard to concentrate in class.

The researchers found that not enough sleep was an important variable: Students who slept for less than six hours at night could not concentrate in class the next day.

You probably know the number called pi. It equals about 3.14159.

Look at the circles below. For every circle, no matter how big or small, one thing is always true:

Circumference ֳ/ diameter = pi.