What factor in an experiment can be changed to determine its effect?

In an experiment, a variable is the element that can be changed or manipulated to observe its effects on the outcome of the experiment. This could be anything from the temperature, the amount of a substance, or the type of material used. By altering the variable, scientists can gather data on how these changes affect the dependent or responding variables, allowing them to draw conclusions about cause and effect.

For instance, if you were testing the effect of fertilizer on plant growth, the amount of fertilizer used would be the variable. By varying the amounts given to different groups of plants, you can assess how it influences their growth rates.

In contrast, constants are conditions that remain unchanged throughout the experiment to ensure that the test is fair, control groups are used for comparison by keeping some factors the same while changing others, and samples refer to the individuals or items selected for the experiment itself. All these components are essential for conducting a valid experiment, but only a variable is specifically altered to observe its effects.