The scientific method is a logical sequence of steps used to test ideas concerning the natural world. The steps include: observing, questioning, hypothesizing (i.e., making an educated guess to answer the question), designing an experiment to test the hypothesis, performing the experiment to test the hypothesis, and analyzing results to assess the validity of the hypothesis.

Variables must be identified when forming hypotheses and designing experiments to test hypotheses. These are agents that may change the outcome of the experiment or be changed by the outcome of the experiment. In particular, the experimenter must identify the independent and dependent variables when forming and testing the hypothesis. The identification of the independent and dependent variable during hypothesis formation and testing is important because the hypothesis predicts: if the independent variable changes, then the dependent variable will change. More specifically, the independent variable is the variable that is intentionally changed by the experimenter, whereas the dependent variable is the variable that changes in response to the independent variable and is measured by the experimenter.

The experimenter must also identify control variables prior to testing the hypothesis and when designing the experiment. Control variables are other variables that may change the dependent variable. Control variables must be kept constant throughout the experiment to ensure that any change in the dependent variable results from the intended change in the independent variable.