More than 5,000 students in Montana attend four-day schools — and according to one district superintendent, these students are falling behind.

Sunburst School District Superintendent Tim Tharp studied four-day school student performance for his doctoral thesis, and this week, the Billings Gazette reported on Tharp’s findings.

The takeaway, from Gazette reporter Matt Hoffman:

“(Tharp) found that in 2011, standardized test scores were slightly below state averages — not uncommon for small, rural and especially reservation schools. But they dipped alarmingly in 2012 and again in 2013, falling farther away from state averages.

“The results stunned Tharp at first.

“’When it jumped out, I completely erased my spreadsheet and started over,’ he said.”

In November, Idaho Education News published an in-depth, five-day series on Idaho’s four-day schools — and their impact on 26,881 students. We found little in the way of conclusive evidence on academics, but found some troubling gaps between four- and five-day schools on recent standardized tests.

Aside from that, there are some striking similarities between four-day schools in Montana and Idaho. Some teachers and administrators openly embrace the schedule, saying the calendar improves student attendance and helps districts recruit teachers. Hoffman also cites a study we reported on in our series — one that indicated improved student performance in four-day schools in Colorado.