Controlled experiments are conducted under conditions that maintain constant variables, illuminating the true effect of the independent variable on the dependent variable. Understanding control groups and control variables is fundamental for effective experimental design.

An example of a control in science would be cells that get no treatment in an experiment. Say there is a scientist testing how a new drug causes cells to grow. One group, the experimental group would receive the drug and the other would receive a placebo. The group that received the placebo is the control group.

A control variable is any factor that is controlled or held constant in an experiment. A control variable is any factor that is controlled or held constant during an experiment. For this reason, it’s also known as a controlled variable or a constant variable. A single experiment may contain many control variables.

In an experiment, controls work alongside independent variables (factors that are manipulated), dependent variables (outcomes that are measured), and constants (factors that remain the same) to ensure validity and reliability.