What is the independent variable in an experiment?

• A. The variable that is measured
• B. The variable that is manipulated or changed
• C. The variable that remains constant
• D. The variable that is observed

Answer: (B)

In an experiment, the independent variable is the one that is manipulated or changed by the experimenter to observe its effect on the dependent variable. This variable is central to the experiment as it establishes the conditions for testing the hypothesis. By intentionally changing this variable, researchers can study how it impacts outcomes or behaviors in the system being tested.

For example, if a scientist is testing how different amounts of sunlight affect plant growth, the amount of sunlight is the independent variable that is varied. As the experiment progresses, researchers will observe changes in growth patterns, which are measured as the dependent variable.

The other options reflect different aspects of experimental design, such as measured variables or constants, but they do not capture the role of the independent variable as the factor being altered to investigate its effects.