<P> In the United States, the K--12 school calendar is determined by the individual states, and in some cases by the local school district, so there is considerable variation . The academic year typically consists of two 18 - week semesters, each divided into two nine - week marking periods (or quarters) or three six - week marking periods, and constituting 170 to 186 instructional days (with an average of 180). An instructional week is five instructional days, measured Monday--Friday at all public and most private schools; Saturday--Wednesday or Sunday--Thursday at Muslim private schools; and so on . Grades are usually reported per marking period, but major examinations are given per semester or per year . </P> <P> The traditional start date for the school year has been the Tuesday following the first Monday in September (the day after Labor Day). Though some schools still keep this tradition, many schools now start in the last two weeks of August and some schools (especially private ones) may start as late as the end of September or the first week in October . There are also some schools, especially in the southern tier of the United States, that begin at the end of July and early August . The school year ends 42 instructional weeks after it begins . Also, some schools are now moving to the first Wednesday in September (usually two days after Labor Day, unless it falls on September 1 or 2) to allow a short week as students adjust to being in school again . </P> <P> School holidays in the United States vary by jurisdiction . They include federal, state, and local holidays, all or only some of which may be observed by an individual school district . In addition to these legal holidays, there are vacation periods of varying length . Most if not all schools observe the Thanksgiving holiday, and extend it include the day after Thanksgiving since it is a Friday . There is usually a recess of about two weeks during the winter holiday period at Christmas and New Year, with a spring break in March or April that is usually correlated to the holidays of Easter and / or Passover . </P> <P> Many schools have additional "in - service" days that are holidays for students but workdays for faculty and staff . These days are often used for parent--teacher conferences on student progress, especially in primary school . In secondary school, they are usually used as staff development days . Sometimes schools do half - day in - service days in which students are dismissed early, rather than full - day holidays . </P>

When do primary schools break up for easter