Year-round school calendars "do little to raise achievement and pose a host of logistical problems that are hard for schools and parents to solve," write researchers Paul T. von Hippel and Jennifer Graves in Education Next. "To school leaders who hope that changing calendars can undo pandemic learning loss, we offer this advice: Don’t do it."
One reason year-round students don't learn more is that they don't get more learning time, Von Hippel and Graves write. Typically, year-round schools offer a "balanced" calendar providing the same 175 to 180 days of instruction. Students gets less time off during the summer and longer breaks during the year.
"Extended-year" models, which may teach for 200 days, are very rare in the U.S.
Potentially, single-track schools can use the longer breaks as “intersessions” for catch-up work or enrichment. However, this runs into the same problem as summer school, Van Hippel and Graves write. It's hard to fund and staff and even harder to get students to show up.
Flint, Michigan schools adopted a year-round calendar with four weeks of intersession instruction in 2018. "Three years later, the superintendent lamented that not enough struggling students were attending the intersessions," and called for returning to a traditional calendar.