Most school districts could simply switch the start times for their schools and accommodate all age groups for optimum learning. But, for some reason they don't. It might be sports schedules, transportation schedules, or simply the preference of older administrators who want to arrive at certain times for work. Whatever the reason, parents owe it to their kids to ensure that school start times match peak learning times in their communities.
Oh - and here is a bonus for you. When adolescents get home from school later in the day, they are less likely to use drugs, get pregnant, or commit crimes.