Mr. Doe wanted to perform an experiment to determine if doing a class review before a test would increase test scores. Mr. Doe normally does not review. To perform this experiment, Mr. Doe reviewed material with the 2nd period before a test and did not review with the 3rd period. After grading papers, he found that the 2nd period had an average grade of 93 and the 3rd period had an average grade of 72. He determined that reviewing before a test might increase test scores. Find the control group and experimental group. Find the independent and dependent variables.