See Who Dropped Your Course
Although ISIS shows faculty who is both enrolled in their course and who dropped their course, CoursePlus has only shown students currently enrolled in a class. As of Friday, January 30, 2015, CoursePlus now records when students drop a course and that information is shown to faculty and TAs at the bottom of the class roster page. If a student dropped a course prior to Friday, Janauary 30, 2015, they won't show up on the bottom of the class roster page, but all drops will show moving forward.