Final answer:
An experiment is conducted under controlled conditions to test a hypothesis by manipulating variables and measuring their effects while maintaining a control group for comparison.
Step-by-step explanation:
An experiment is a method of scientific investigation carried out under controlled conditions to test the validity of a hypothesis. It includes manipulating one or more variables while keeping others constant to isolate effects on the dependent variable. The control group serves as the standard of comparison, untouched by the experimental treatment. Variables that change are known as experimental variables, while those kept constant are control variables. An example would be observing the coat color in rabbits at different temperatures to see if temperature (independent variable) affects coat color (dependent variable).
The experiment will have one or more variables, which are parts of the experiment that can vary or change, and one or more controls, which are parts of the experiment that do not change. For example, in a study testing the growth of algae in freshwater ponds, the presence or absence of phosphate would be variable, and the experimental tanks with phosphate and control tanks without phosphate would be used to compare the results.