What part of the scientific method tests a hypothesis?

The experiment is the part of the scientific method that tests a hypothesis.

A hypothesis is a proposed, testable explanation for an observation. To evaluate it, researchers design an experiment that changes or examines selected variables while collecting measurable evidence. The results can support the hypothesis, contradict it, or show that the question needs to be tested more carefully.

A well-designed experiment usually identifies an independent variable, which the investigator changes, and a dependent variable, which is measured. Controls and comparison groups help show whether the observed outcome is actually connected to the factor being tested. Repetition and careful record-keeping make the findings more reliable.

People sometimes treat the scientific method as a rigid checklist, but real research is more flexible. Scientists may return to earlier steps, revise a hypothesis, or conduct several experiments. Also, an experiment does not “prove” a hypothesis permanently; it provides evidence that may continue to be tested as new observations become available.