TWO-STAGE EXAMS CAN REDUCE THE ACHIEVEMENT GAP IN UNDERGRADUATE OCEANOGRAPHY AND GEOLOGY CLASSES
We analyzed 289 student scores on 14 two-stage midterm and final exams given by six different instructors. All 289 students completed both stages of the exam. For each exam, the mean group score (stage two) exceeded the mean individual score (stage one), and all gains were statistically significant at α=0.05. Students who scored in the bottom quartile of the individual exam experienced the greatest mean improvement from individual to group. Students who scored in the top quartile of the individual exam had a lower, but still statistically significant, mean increase. The vast majority of groups had a group score that exceeded the scores of all individuals in that group, which argues against the theory that the increased group score is due to group members simply copying answers from the top-performing individual in their group. A cohort analysis revealed that groups containing all combinations of high- and low- performing students during stage one experienced statistically significant mean gains in exam scores, and selecting groups to include a mix of high- and low- performing students can be a highly effective way to proactively reduce the achievement gap.