Variable
Variable explained in an easy to understand way:
Imagine you're adjusting the thermostat in your home to find the perfect temperature for everyone. In science, the variable that can change in an experiment is similar to the thermostat setting that you adjust to see how it affects the comfort level. Just as the thermostat setting is a factor you can change to see how it impacts the room's temperature, a variable in an experiment is an element that you alter to observe its effects on the outcome.
Practice Version
Variable: The factor that can change in an experiment is a variable. In simple terms, a variable is something you can change or measure in a science experiment to see how it affects the outcome.