Year-round school calendars take the usual 175-180 instruction days of the school year and redistribute them, replacing the usual schedule – nine months on, three months off – with a more “balanced” schedule of short instruction periods alternating with shorter breaks across all four seasons of the year. Over the past three decades, the number of schools using year-round calendars has increased ninefold, from 410 in 1985 to 3,700 in 2011-12 (Skinner, 2014). Over 2 million children now attend year-round schools – as many as attend charter schools – yet year-round schools have attracted relatively little attention from researchers and the public.
In this chapter, I review the evidence for the effects of year-round calendars on test scores. Once thought to be positive, these effects now appear to be neutral at best. Although year-round calendars do increase summer learning, they reduce learning at other times of year, so that the total amount learned over a 12-month period is no greater under a year-round calendar than under a nine-month calendar. I also review evidence that year-round calendars make it harder to recruit and retain experienced teachers, make it harder for mothers to work outside the home, and reduce property values. When students' schedules are staggered, year-round calendars do offer a way to reduce school crowding – an alternative to busing or portable classrooms, and a low-cost alternative to new school construction.