For the last 40 minutes of each day, Vickie Seivley and every other teacher at Gilcrest Elementary works with students on "authentic literacy" — an intense focus on reading and writing designed to squeeze the most out of an abbreviated, four-day school week.

Last spring, the 1,800-student Weld County RE-1 school district decided to follow a strategy born of the energy crisis in 1980 and embraced by dozens of Colorado districts — and lately, by still more amid budget-slashing economic times.

By stretching the school day and shortening the week, districts balance their budgets with cost savings on support staff, maintenance, food service and transportation. They face inevitable push-back from parents with day-care concerns but avoid tough cuts in other areas.

"You have to change your mind-set on how you teach and instruct," said Seivley, whose second-graders come largely from low-income homes in the district just south of Greeley. "My top challenge was to make sure that I was still able to meet their needs as I would in a traditional calendar."

Since the recession hit in 2007, 18 Colorado districts have switched to four-day school weeks — a nearly 30 percent increase. The state jumped from 62 to 80 districts with schools that won state approval for a shift from the traditional 160-day calendar.

Most cited financial reasons for the change.

While research on the academic impact of the four-day week is sparse, both national surveys and a Colorado Department of Educationstudy released this yearpoint to similar student performance in four- and five-day weeks.

The savings, though, are less than you might think. A 20 percent reduction in school days seldom nets more than 2.5 percent slashed from the overall budget,according to a national studyby senior policy analyst Michael Griffith of the Denver-based Education Commission of the States.

The vast majority of school spending goes to educator pay and benefits. None of the districts surveyed reduced those because instructional staff was required to work the same number of hours across the school year. Despite relatively meager savings, percentage-wise, some districts jumped at the chance to avoid losing teaching positions.

So far, there's optimism in Salida, whose school district is a little more than one year into a three-year commitment to the schedule that saves it about $150,000 against a total budget of roughly $19 million.

"We were getting down to whether we were going to cut teaching positions or try the four-day week," said Superintendent Darryl Webb, noting that in the first year of the new schedule, test scores ticked up.

He doesn't credit the new schedule for that, but he does think that a heightened sense of academic urgency in the four-day week has led to an increase in attendance among both students and staff.

"As we suspected, it's a lot easier to adjust for middle and high school parents and not near as easy for elementary school parents," Webb said. He has scheduled an October workshop to address lingering parent issues.

Critics of the four-day week, while acknowledging that even minimal savings can mean a lot to a district, see the practice as adding to an already troubling summer learning loss and flying in the face of trending reform efforts aimed at expanding instructional time.

"I know some smaller rural districts have been doing it a long while and they have strategies that seem to be working," said Jennifer Davis, president and co-founder of the Boston-based National Center on Time and Learning. "But the policy decision, at a time when we're trying to upgrade our education system in America, is in the wrong direction."

In Grand Junction, Mesa County Valley School District 51 considered the move to a four-day week to mitigate continued deep budget cuts — and watched as some smaller surrounding districts took the leap.

Although the district noted that there seemed to be no firm evidence of negative effects on learning, its hesitation stemmed from the fact that districts using the strategy tend to be much smaller than its own 21,000-student population.

Several other factors moved Grand Junction to shelve the idea, at least for now. The district's anticipated $12 million budget shortfall didn't materialize due to an improved state funding picture. And the potential savings amounted to only about 1 percent of the $150 million budget, which didn't seem to warrant the possible day-care problems it would create for many families.

"It was something we wouldn't reject permanently — but not this year," said Superintendent Steven Schultz. "We're trying to find ways to add days to the calendar. There could be a four-day week in our future, but with more days than we currently have."

In Weld RE-1, the savings from taking Mondays off amounts to about $360,000 — almost all from support staff salaries — or 1.7 percent of the district's $21 million budget.

But when the announcement came last spring, parents pushed back. Hard.

Amanda Owens, who has two daughters in school and also served on the district finance committee, said some might have been outraged because the budget slashing up to that point — nearly $5 million over three years — hadn't touched them directly.

"There was a firestorm, honestly," said Owens, a work-from-home travel agent and sometime substitute teacher. "We'd been talking about budget cuts for a long time, but now that it's touching you, it's different."

Studies on the effects of the four-day week recount similar dynamics across the country: an initial backlash, powered largely by looming day-care challenges, eventually dissolves into widespread support.

Mike Williams, a math teacher at the district's South Valley Middle School, reacted like many colleagues, with surprise at the decision and uncertainty over what it would mean for students.

"We know kids regress over the summer," he said. "I was wondering how three-day weekends would play into that and what would happen to student learning. I was kind of fearful."

Just seven weeks in, no red flags have been raised on student performance. Teachers find more hours for lesson planning and tend to more finely tune their instructional time. Seivley, the second-grade teacher at Gilcrest, has used the extra off day to visit other districts and learn their strategies for dealing with low-income and minority students.

And Superintendent Jo Barbie has started to hear some parents express appreciation for the additional family time.

"I think we're winning them over," she said. "It's working for us."