School gets out hours before most parents with day jobs get home.
The system ensures that kids are unsupervised. Schools have stuck with the same old for much of the 20 th Century. Kids don't go to school in the summer because when their great grandfathers and great grandmothers were school age, families needed them home on the farm to do chores that helped support the whole family. Even though mechanization removed the need for child labor on farms and ranches and even though most families left the nation's farms and ranches a couple of generations ago, school schedules still haven't changed. Extracurricular activities and part-time jobs haven't filled the gap for a lot of older kids.