Figure 1.

Average 2010–2014 weighted GPA for each cohort of students who experienced the change in school start times (each line connects points for a given cohort). For the 2009 cohort, the two years prior to start time change (10^th and 11^th grades) are plotted along with one year after change (12^th grade). For the 2010 cohort, two years prior (9^th and 10^th grades) and two years after the time change (11^th and 12^th grades) are plotted. For the 2011 cohort, one year prior to the time change (9^th grade) and two years after the time change (10^th and 11^th grades) are plotted.