(NewsNation) — A four-day school week can help districts compete for teachers and cut some costs, but may also come with student delays, according to RAND.

Researchers interviewed nearly 500 students, parents, teachers and principals across New Mexico, Idaho and Oklahoma, and surveyed more than 1,300 parents and 6,500 middle- and high-school students.

85% of the students attending four-day schools said they liked the shorter week, and 89% of elementary school parents said they were satisfied with a shorter schedule.

RAND says school districts were able to cut costs by not running on Fridays, but the savings only accounted for a small percentage of the annual budget.

According to the researchers, student attendance may have seen a slight improvement at four-day schools but children possibly fell behind in learning.

RAND says Math and English test scores didn’t fall when schools made the switch to a four-day week, but they didn’t grow as fast as they did in schools that stuck to a five-day schedule.

“That meant students in the four-day districts fell behind a little more every year,” a RAND Review read. “After eight years, the gap was roughly equivalent to the achievement losses that schools saw during the pandemic.”

Andrea Phillips, a former middle school teacher who co-led the study, added: “The teachers and parents and administrators that we talked to were quick to say ‘Year over year, we see our rank in the state the same or improving; we see our test scores improving. And that was true. They were improving. It’s just that their rate of improvement would have been higher if they had stayed at five days.”

Schools with four-day weeks usually start their days earlier and finish later. The concept has gained popularity in recent years.