French schoolchildren have some of the longest school days in the world, I believe; some of them start at 8h30 in the morning and don’t finish till 17h30 in the evening, although they might have two hours off for lunch at mid-day.
What that buys is a great school holiday schedule, unless you’re a pair of working parents; in which case it can become a nightmare of workarounds. Instead of three solid months of summer vacation, like most American children, French children have a fairly short amount of time in the summer, but they get ten days to two weeks in October (the Toussaint holiday), two weeks at Christmas, two weeks in February or early March, and two-and-a-half weeks in April (usually). The month of May is full of three- or four-day weekends, and then the children have school until the end of June. The calendar is staggered according to three regions; Paris has one calendar, and the rest of France is divided in half.
This means that if you are traveling in France, it’s a good idea to keep an eye on the calendrier des vacances scolaires to make sure you’re not trying to get somewhere on a Day of Great Departures (jour de grand départ) if you can possibly avoid it.