DURHAM, N.C. — Some high school students and their teachers are gearing up for a major change.

Durham Public Schools

is moving from a traditional schedule to a block schedule. Three-quarters of the high schools in North Carolina have already made the move.

"For Durham, this is a big change," Riverside High Principal Jim Key said. "It provides more opportunity to take more classes and it provides greater choice."

Instead of six classes over one year, students will take four-90 minute classes each semester. It is similiar to a college schedule. The goal is to give students more flexibility.

Block scheduling does not just give students an opportunity to take more classes. It enables students who fail a class more of an opportunity to make that class up.

"They can immediately in the next block, say the spring, repeat the class or take an alternate version of the class," teacher Steven Unrhue said.

Supporters admit the new system is not without flaws. While classes will be more concentrated, teachers will actually spend less time with students.

"Instead of 180 days of 55 minutes, I'll have 90 days at an hour and an half," Unrhue said.

All of Durham's seven high schools will convert to the block system except the School for the Arts and the Josephine Clement Early College High School.

Last year, all of Wake County's non-magnet high schools converted to similar 4-by-4 block scheduling. Two-thirds of North Carolina's schools of distinction use block scheduling. Also, half of the country's best performing high schools have moved to the block system.