A researcher wants to know if giving students chocolate before an exam will improve their scores. Two groups of students take the exam, but only one group gets chocolate first. What is the independent variable in this experiment?

Chocolate (Independent variable)

Explanation:

The independent variable is manipulative. The experimenter can manipulate it. It produces one or more results in a study called the dependent variable. It is called the independent variable because its variation doesn't depend on another variable in an experiment. The independent variable can be controlled or manipulated only by the researcher or experimenter.

For example:

Amount of water and fertilizer provide a tree. Water and fertilizer is an (independent variable) which can be manipulated by the experimenter.

Result: Height of the tree depends on water and fertilizer quantity (dependent variable) which can not be manipulated by researcher.