Question

An experiment in which only one variable is changed is a (an) ________ experiment. Help!

Answer 1

Answer;

D. controlled

An experiment in which only one variable is changed is a controlled experiment.

Explanation;

-A control experiment is an experiment where the researcher only changes one variable at a time in order to isolate the results.

In a controlled experiment, most conditions are constrained so that they do not change. One or two other conditions are then changed and measured by the experimenter. These are known as the independent variables.

For example; An experiment where all subjects involved in the experiment are treated exactly the same except for one deviation.

Answer 2

All controlled experiments would have only one variable. If there were more than one variable the outcome of  your experiment could be for multiple reasons and thus you would not be able to test whether your specific hypothesis was valid.