In a scientific experiment , a__ is any factor that can change or be changed?

In a scientific experiment, a Variable  is any factor that can change or be changed

Explanation:

In a scientific experiment, scientists observes the change of a factor and its effects on other things. These changing things of an experiment are known as Variables. It is a factor or a condition that can be present in different types.

Variables are of three types- Dependent, independent and controlled variables.

Scientists change the independent variable, dependent variables are observed by them to figure out the response of that thing to that change and controlled ones are constant.  Variables that can be measured are widely used by the scientists in an experiment.  

you must remain stopped until the stop signal is retracted and the red lights are turned off. approaching traffic in the opposite roadway of a divided highway shall not be required to stop, even if the school bus has the stop-arm extended and the alternately flashing warning signal lamps on.

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