Here's why:
* Independent variable: This is the factor that the scientist intentionally changes or manipulates in an experiment. It's the "cause" in the cause-and-effect relationship they are investigating.
* Dependent variable: This is the factor that is measured or observed in response to the changes in the independent variable. It's the "effect" in the cause-and-effect relationship.
* Controlled variables: These are all the other factors that could potentially influence the dependent variable, but the scientist keeps them constant throughout the experiment to ensure that only the independent variable is affecting the results.
Example:
Let's say a scientist wants to test the effect of different types of fertilizer on plant growth.
* Independent variable: The type of fertilizer used.
* Dependent variable: The height of the plants.
* Controlled variables: The amount of water, sunlight, and soil type would need to be the same for all plants.
The scientist would control the amount of water, sunlight, and soil type to ensure that any differences in plant height are solely due to the different types of fertilizer used.
