High school students who change their class schedules after the start of the school year may miss class time before their schedules are finalized. This loss of class time is expected to lead to a loss of learning opportunities, and thus to lower student achievement. We examine a school with an unexpectedly large number of such schedule changes. Contrary to our expectation, students who were not in class because they were changing schedules had achievement equal to students who were in class, even when the students changing schedules missed many days of class. While this indicates that students were not penalized for schedule changes, it also suggests that all students had reduced opportunities to learn.