Four-day school weeks (4dsw) have become a growing trend deployed by school districts in order to combat teacher shortages. 850 school districts across the country have dropped a fifth day of instruction, up from 650 in 2019. While more popular in rural districts, four-day school weeks are catching on in metropolitan areas as well.

The rapid growth in popularity since the pandemic began may have contributed to lower test scores in reading, math, history and civics among U.S. eighth graders in 2022. According to data compiled by a policy group at Oregon State University, less classroom time correlates directly with lower test scores and academic achievement.

“A comparison of English language arts and math test scores showed that students on the 4dsw have lower scores, over time, when compared with peers on a five-day schedule,” the RAND corporation said in a summary of its study. A different study also found higher absenteeism and lower on-time graduation rates at schools with a four-day school week.

There have been pros reported as well, which include less burnout and more family time for students and teachers. A study also found less bullying taking place in districts with four-day school weeks.

“Given these mixed findings, communities are likely to make different choices about the 4dsw depending on their goals and the local context,” the RAND corporation said.