The quantities that are able to change in an experiment or a research are called as the variables. It is a trait or any factor that exits in different types or amounts. An independent variable is changed by the scientist or the experimenter in the experiment. Its value does not depends on the experiment.
In the context, there are boxes of two dry samples of sand and they are examined by changing one of the parameter. It is the independent variable that is manipulated in the two samples is the mass of each of the sample.
