Controlled variables must be kept constant so that they can't influence the dependent variable.

Understanding Controlled Variables

1. Definition: Controlled variables, also known as constant variables, are the factors in an experiment that are kept the same throughout to ensure that any observed effect on the dependent variable can be attributed solely to the independent variable.

2. Importance: Keeping controlled variables constant is crucial because if they change, they could introduce confounding variables which might affect the outcome of the experiment. This jeopardizes the reliability and validity of the results.

3. Examples: For example, if an experiment is testing the effect of different amounts of sunlight on plant growth (where sunlight is the independent variable and plant growth is the dependent variable), then controlled variables might include soil type, amount of water, temperature, and type of plant. All these factors need to remain constant to ensure that any difference in plant growth is due only to variations in sunlight.

4. Conclusion: In summary, controlled variables are foundational to experimental design; they help in isolating the effects of the independent variable on the dependent variable, thus ensuring more accurate and reliable results in scientific investigations. Understanding and maintaining controlled variables is essential for any researcher aiming to derive conclusive findings.