New research suggests that shortening the school week may improve elementary school students' academic performance.

Researchers at Georgia State University and Montana State University found that a four-day school week had a statistically significant positive impact on math scores for fifth-grade students, while reading scores were not affected, Consumer Affairs reported.

"What interested me about our results is they were completely opposite to what we anticipated," Mary Beth Walker, dean of the Andrew Young School of Policy Studies at Georgia State, said in a statement. "We thought that especially for the younger, elementary school kids, longer days on a shorter school week would hurt their academic performance because their attention spans are shorter. Also, a longer weekend would give them more opportunity to forget what they had learned."

For the study, researchers compared fourth-grade reading and fifth-grade math test scores from the Colorado Student Assessment Program (CSAP) for students who participated in a four-day school week, versus those who attended a traditional five-day school week, The Independent reported.

The shortened school week did not have negative effects which "was an important result," Walker said.

Four-day weeks have been in place for years in rural school districts in western states, particularly in Colorado, New Mexico and Wyoming. Over one-third of the school districts in Colorado have adopted a four-day schedule. The alternative schedule has also been considered in school districts in Oregon, Missouri, Florida and Georgia.

The shortened school week requires school districts to lengthen the school day to meet minimum instructional hour requirements. Before this study, there was a lack of information on whether the four-day school week affects student performance.

"We thought the longer days might give teachers an opportunity to use different kinds of instructional processes," Walker said. "We also speculated that a four-day school week lowered absenteeism, so students who had dentist's appointments or events might be able to put those off until Friday and not miss school. We thought there might be less teacher absenteeism.

The findings, which are detailed in the journal Education Finance and Policy, re only applicable to smaller and more rural school districts.

Walker said further studies should be performed to understand the effects on urban school districts.