A researcher provides one classroom of college students a list of 20 words to study while classical music plays in the background. Another classroom of college students studies the same list in silence. What method is the researcher using?

The method used by the researcher is classified as an experiment because it involves the manipulation of an independent variable to observe its effect on a dependent variable. In this case, the independent variable is the presence of classical music during the study session, while the dependent variable could be the students' retention or recall of the 20 words.

By assigning one group to study with music and another group in silence, the researcher can systematically compare the outcomes between the two conditions. This design helps in establishing cause-and-effect relationships, which is a hallmark of experimental research. The controlled environment and the direct manipulation of conditions to assess their impact on student performance provide a clear framework for testing hypotheses about the influence of background music on learning and memory.