An experiment is a planned, controlled observation. The investigator controls the situation to observe results that will help answer the question. The factors that are controlled are called variables.

• Independent variables are controlled by the investigator to identify the cause of the results.
• The dependent variable is allowed to change based on the indenpendent variables.
• The data collected about these variables can be used to write an equation which describes the relationship with numbers.

Sometimes the results of an experiment lead to a question or hypothesis that requires a new experiment.