In an experiment, which term refers to the variable you deliberately change to test its effect?

• A. Dependent variable
• B. Independent variable
• C. Control variable
• D. Constant

Answer: (B)

The variable you deliberately change to test its effect is the independent variable. In an experiment, you set this factor at different levels to see how it influences the outcome. For example, if you’re studying how sunlight affects plant growth, you would vary the amount of sunlight (the independent variable) and then measure growth to see the result. The thing you measure—the plant’s height or biomass—is the dependent variable, which shows the effect of changing the independent variable. Other factors that stay the same across all trials are control variables, kept constant to ensure that any observed changes come from the independent variable and not from other influences. A constant is simply a value that doesn’t change, which isn’t what you manipulate to test effects, but it helps keep the experiment fair.