Students in a statistics class were divided into two groups at random. Students in one group were given a set of words to memorize in a room with music playing. Students in the other group were given the same list of words to memorize but in a quiet room. Students in the quiet room were able to remember more words, on average. Is this an observational study or an experiment

An observational study is a study in which the researchers collect data related to what is visible or heard. In this type of study the researchers do not have any control on the variables used for the research work .The researcher do not bring any changes in the behavior of the variables that is they are accepted the way they are.

An experiment is a method used in which the researchers pick up a sample from a group and test them to get a proof or knowledge about something.

Both Observational study as well as an experiment are used in statistics social sciences and psychology etc.

Thus the case given here is an experiment because there is no alterations done with the variables.