In October 2011, Montana passed a law that allowed public schools to implement four-day school weeks, according to the Office of Public Instruction. But that begs the question: Are four-day weeks more successful than five?

Since the law was passed, more and more schools have adopted the model, including Victor School, Drummond High School and Potomac. Now, NBC Montana reports that 100 small, rural schools with some 5,000 students now use a four-day school week.

The Associated Press reports while districts that switched say student performance has typically held steady or improved, there's little hard data on how a four-day week affects academics.

The Billings Gazette showed some declines, but also increased improvement as well. Sunburst Schools Superintendent Tim Tharp said there was an initial improvement or holding steady for the first few years after the four-day week is instituted. But after that, the Gazette said his research shows performance drops