IRENE, S.D. – When the nearly 300 students of the Irene-Wakonda School District returned to school this week, they found a lot of old friends, teachers and familiar routines awaiting them. But one thing was missing: Friday classes.

This district in the rolling farmland of southeastern South Dakota is among the latest to adopt a four-day school week as the best option for reducing costs and dealing with state budget cuts to education.

“It got down to monetary reasons more than anything else,” Superintendent Larry Johnke said. The $50,000 savings will preserve a vocational education program that otherwise would have been scrapped.

The four-day school week is an increasingly visible example of the impact of state budget problems on rural education. This fall, fully one-fourth of South Dakota’s districts will have moved to some form of the abbreviated schedule. Only Colorado and Wyoming have a larger proportion of schools using a shortened week. According to one study, more than 120 school districts in 20 states, most in the West, now use four-day weeks.

The schools insist that reducing class time is better than the alternatives and can be done without sacrificing academic performance. Yet not all parents are convinced.

“The kids are going to suffer,” said Melissa Oien, who has four children in the school and serves as vice president of the parent-teacher organization. “Of course they will. They’re missing a whole day of school.”

Irene-Wakonda’s predicament, like those of many other rural districts in the Great Plains, is compounded by declines in population and enrollment. The two towns, which are eight miles apart, combined their school districts in 2007 to save money. Wakonda got the elementary school and Irene the middle and high schools. Farming is the largest share of their economies, although some people commute to jobs in Yankton or Vermillion.

Johnke, the superintendent, said the district will add 30 minutes to each day and shorten the lunch break to provide more class time Monday through Thursday. In elementary school, recess and physical education classes will be shortened.

The changes won’t entirely make up for losing Friday, Johnke said, but the district will still exceed the state’s minimum standard for class time and will teach all the required material.

“We feel they’ll get the same instruction. It’ll have to be done a little bit differently,” he said.

South Dakota’s Republican-controlled Legislature slashed aid to schools this spring by 6.6 percent to help close a $127 million budget gap.

Republican Gov. Dennis Daugaard said state revenue has not grown in three years while costs have risen for medical services for the poor.

He ruled out revenue increases. “I believe in shared sacrifice,” Daugaard said earlier this year. Education groups hope to put a tax proposal on the 2012 ballot.

In South Dakota, the cut comes in a state that, according to recent census data, already ranked 44th in state spending per pupil. The Associated School Boards of South Dakota estimates another $233 million a year is needed to adequately fund schools.

Many districts reduced staff or eliminated programs to make up for the lost money. The number of districts going to four-day weeks has nearly doubled in just two years.

Wayne Lueders, the recently retired director of the Associated School Boards, said a four-day school week won’t actually save much because schools still must pay salaries and benefits, “but every dollar counts in this current situation.”

Schools can save on busing, food and other operations.

South Dakota’s state education secretary, Melody Schopp, says schools that have switched to four days haven’t suffered in achievement tests.

In Deuel, a 500-student district that shortened its week four years ago, Superintendent Dean Christensen said as much as $100,000 a year has been saved and the failure rate has declined, which he attributed to more time for tutoring and teacher training.

“It’s not something to be scared of,” Christensen said.