What is a variable in a scientific experiment?

• A. A fixed factor that remains constant
• B. A measure of the experiment's outcome
• C. A factor that can be changed or controlled
• D. A summary of the data collected

Answer: (C)

In a scientific experiment, a variable is a factor that can be changed or controlled to test its effects on other variables. This means that researchers manipulate variables to observe how these changes influence outcomes. For example, if you were testing how different amounts of sunlight affect plant growth, the amount of sunlight would be a variable you control. By altering this factor, you can gather data on how it impacts the growth of the plants.

This understanding of variables is fundamental in experimentation, as it allows scientists to isolate specific factors and learn about the relationships between them. Without controlling the variables, it would be difficult to draw meaningful conclusions from the experiment's outcomes. Thus, recognizing what constitutes a variable—and being able to identify those that can change—enables researchers to design robust and effective experiments.