what is the rule for when easter is
Computus For most of their history Christians have calculated Easter independently of the Jewish calendar. In principle, Easter falls on the Sunday following the full moon that follows the northern spring equinox (the paschal full moon). However, the vernal equinox and the full moon are not determined by astronomical observation. The vernal equinox is fixed to fall on 21 March (previously it varied in different areas and in some areas Easter was allowed to fall before the equinox). The full moon is an ecclesiastical full moon determined by reference to a lunar calendar, which again varied in different areas. While Easter now falls at the earliest on the 15th of the lunar month and at the latest on the 21st, in some areas it used to fall at the earliest on the 14th (the day of the paschal full moon) and at the latest on the 20th, or between the sixteenth and the 22nd. The last limit arises from the fact that the crucifixion was considered to have happened on the 14th (the eve of the Passover) and the resurrection therefore on the sixteenth. The "computus" is the procedure of determining the first Sunday after the first ecclesiastical full moon falling on or after 21 March, and the difficulty arose from doing this over the span of centuries without accurate means of measuring the precise tropical year. The synodic month had already been measured to a high degree of accuracy. The schematic model that eventually was accepted is the Metonic cycle, which equates 19 tropical years to 235 synodic months.
Spring break In the United States, Spring break at the college and university level can occur from March to April, depending on term dates and when Easter holiday falls. Usually, Spring break is about one week long, but many K–12 institutions in the United States schedule a two-week-long break known as "Easter Break," "Easter Holidays", or "Easter Vacation", as they generally take place in the weeks before or after Easter.[citation needed] However, in the states of Massachusetts and Maine, schools typically schedule Spring break for the week of the third Monday in April to coincide with Patriots' Day.