Data is available and the results seem mixed and difficult to interpret so far, here's an article with links to a bunch of studies: https://hechingerreport.org/

Data is available and the results seem mixed and difficult to interpret so far, here's an article with links to a bunch of studies: https://hechingerreport.org/proof-points-seven-new-studies-on-the-impact-of-a-four-day-school-week/ https://hechingerreport.org/proof-points-seven-new-studies-o.... It seems like most studies find either no effect on academics or a small negative effect, and sometimes positive social effects like reduced bullying. One point I found interesting: > The four-day work week is an attractive work perk in rural America that may lure better teachers. This makes sense but obviously would disappear if the four-day week became widespread.