Prince William high school students will move to a common schedule next school year that will require students to take seven classes all year long.

The block schedule, called 7AB, will require students to take three 90-minute classes on Mondays, Wednesdays and Fridays and three different 90-minute classes on Tuesdays and Thursdays. Students also will have a 45-minute first period every day. Three high schools in Prince William County already follow a schedule similar to 7AB: Gar-Field, Hylton and Stonewall Jackson.

The other high schools have followed a different form of block schedule called four-by-four: students took four 90-minute classes in the fall, followed by four different classes in the spring.

Superintendent Edward L. Kelly recommended that the county move to a common schedule because of the specialty school program, which allows students to pursue different interests in high schools outside of their normal attendance boundaries. Switching from one schedule to another makes transferring too cumbersome, he said. A common schedule also makes it easier to handle grade reporting and standardized testing.

School Board Chairman Lucy S. Beauchamp said the 7AB schedule was a good compromise, but that she would have liked to see another option, an 8AB schedule. Under that plan, students take eight classes a year on alternating days. A committee of teachers, parents and students had said that either 7AB or 8AB would be an acceptable schedule.

"I had hoped that the response would come back that we could do the 8AB," Beauchamp said. "But it would have cost us too much money" in books and additional personnel.

Other School Board decisions made last week:

* The 2000-2001 school calendar was modified so that "Fall Break" will now be referred to as "Thanksgiving break." School Board member Steven Keen (Woodbridge) had pushed the issue, saying that referring to the holiday period by the generic term "fall break" did a disservice to the Thanksgiving celebration. Spring Break and Winter Break will retain their names.

* Eighth-grade students won't have to take a Standards of Learning exam, but they will have two semester exams. The change to the eighth-grade world history curriculum is the second that the School Board has made in two years. Last year, they stripped a credit from the course to encourage students to take more credit-bearing social studies classes through their high school years.