Despite slim savings, more Colorado districts opt for 4-day week - The Denver Post

As someone who taught for three years in a 4-day week school, here are the major adaptations I remember: getting used to long days and short nights (especially when you coached after school), extra-curriculuar events had to be scheduled on weekends so school nights weren't interfered with, and I became super-conscious about giving up instructional time for assessment time. Whenever possible, I tried to work in small assessments during a regular instructional day. I'm not surprised that 4-day weeks don't save all that much money, or that their academic performance isn't much different than regular schools. But at some point content coverage can be important, and you just can't cover as much as you can when you have more days -- not easily in math, anyway.