MERIDIAN, Idaho — The 20-foot cross was removed from the church steeple two years ago, not long after the Compass Public Charter School moved into the building.

The religious imagery inside is discreetly hidden while 420 students study math, reading and science. A large room with a vaulted ceiling and stained-glass windows serves as the band room, and a curtain covers a small cross above the pulpit.

This charter school in a former dairy town of 71,000 isn't the only one with a unique home.

In a state that has embraced alternatives to the traditional classroom, 31 public charter schools have found themselves setting up shop in everything from a former plant nursery and pet store in Coeur d'Alene, to a strip mall in Garden City and former athletic center in Boise.

Together, the schools serve some 11,000 students. But unlike traditional public schools, they cannot get money from property taxpayers to buy buildings through bonds or levies.

"That is the largest financial challenge charter schools face," said Shirley Rau, school choice coordinator for the state Department of Education. "They are borrowing at the same rate as other nonprofit facilities."

Idaho charters, approved by a 1998 state law, operate with state money based on average daily student attendance, just like traditional public schools. But to raise money for property, teachers, parents and community members seek out investors or borrow from banks to buy facilities.

A third of Idaho charter schools started out in portable trailer classrooms, typically in rural areas of the state where facilities are harder to find, Rau said. Many of these charters have since purchased or built facilities, but some still operate from mobile classrooms.

"What you'll see is a big farm field with trailers," Rau said, adding that a charter school set to open next year in northern Idaho is "probably going to end up in a furniture store."

All but two of the 15 charter schools that own facilities did so with backing from investors, loans, heavy community fundraising and by saving chunks of state money they get based on student attendance.

"Most of this has happened in the last three years," Rau said. "They've only just been able to manage."

The Idaho Arts Charter School moved into a new building this year after years of renting an old church and using nine trailers to hold nearly 600 students, grades K-12. The school is paying back a 30-year, $7.5 million loan from Wachovia Corp. used to buy the facility, said Jackie Collins, Idaho Arts Charter School director.

"There wasn't any area banks that were willing to take the risk," Collins said.