Damaging to extra-curricular activities.  A lot of extra-curricular activities take place during summer holidays. Summer camps, trips abroad - even debating competitions. Summer holidays are a sensible time to hold such activities, partly due to the weather but also because different regions or school boards often have different vacation schedules and summer is the only time when students are all likely to have free time. Year-round schooling would reduce the opportunities for such activities.  Some families use long holidays to arrange extra tuition in certain subjects, either as remedial education or to give their children an advantage [1] . Year-round schooling would make it harder for families who wish to exercise this choice, too.  [1] “Summer School”, US Education Commission of the States, 2011.