The school year usually starts in late August or early September, and goes until late May or early June. There is usually a break of around 2 weeks in late December, and a week long break in April. The school day is 8:00 or 8:30 am to around 3:00pm.
@Tyler-H Though start and end times can differ depending on what grade level you are talking about. When I was in elementary school I got in at around 9am and got out at around 3 but in highschool I started at 7:30 (with an optional 0 period before it, that no one went to) and got out between 2:15 and 3, depending on the day.