Prince George's County public schools, which 18 months ago began an experimental program of isolating students with behavior problems in special study centers, have expanded the program this year to include 28 of the 43 junior high schools in the county.

"There is very little doubt in my mind that it's a good disciplinary tool," said Robert C. Nabors, supervisor of pupil personnel for the school system. Nabors oversaw implementation of the program in March 1977 at Roger B. Taney and Thomas Pullen junior high schools and Crossland Senior High School.

Students with behavior problems, such as being disruptive in class or abusive to a teacher, guilty of fighting, insubordination, theft or class cutting, are sent to the principal's office for disciplinary action. Before the new program began, the usual punishment would have been a short-term suspension from school. But for the last 18 months, administrators at the three schools have had the option of isolating such students.

Instead of being suspended, students are sent to a special room called a Supervised Discipline Center. There, behind locked doors and in grim and Spartan surroundings each student spends up to three days seated alone at a desk with his or her school books.

The students are not permitted to speak to other students, nor are other students allowed to speak to those in the discipline center. In the center, each student's desk faces a barren wall, and partitions on each side of the desk seal off visual contact with any classmate.

The isolated students are not allowed in the cafeteria at lunchtime; instead, they eat brown bag lunches at their desk. Twice a day, once in the morning and once in the afternoon, each student is allowed to go to a restrooms but a faculty member must be along. If students need to use a restroom more often they are referred to the school nurse.

"We've found it to be a very effective system," said Bette L. Lewis, principal at Taney.

"There isn't a teacher here who doesn't think it's a good system. We're all committed to it."

From the beginning, the centers were intended as an alternative to student suspensions and an experimental way of coping with mounting concerns over discipline problems at schools throughout the county.

"It keeps the child in school and he doesn't get behind in his work," said Nabors. "The students don't like it because of the social isolation. They'd almost rather be suspended. But we've had good success in making students behave while they're in there."

While statistics have not yet been compiled for the last academic year, data for the first three months of the centers' operation showed a drop of more than 50 percent in the rate of student suspensions.

Between March 11, 1977, when the centers began operating at Crossland, Pullen and Taney, and the end of school on June 16 of that year, 164 students were suspended from the three schools. For the same three months a year earlier, 330 students were suspended at Taney, Crossland and Pullen.

In the same period, 348 students were sent to the discipline centers for periods ranging from one to three days.

Only 41 students had to be sent to a discipline center more than once, a fact school officials cite as evidence that the centers are an unpopular but effective discipline tool.

"I've had students come to me and beg to be suspended instead of being sent to the center," said Lewis. "When they're suspended they're free to roam around and do whatever they want."

"They're very social at this age. They really miss being with their friends," said Lorenza Robinson, principal at Pullen. "When you pull them out of the mainstream, it really has an impact.

"A kid who cuts class probably doesn't want to be in school in the first place. So it's not much of a punishment to suspend the class cutters."

Each center has a full-time faculty member and a full or part-time aide. The faculty members picks up all classroom assignments from the students' regular teachers, and students are not permitted to return to regular classes until all assignments have been finished.

"If a student is suspended from school and he misses a test, that's not a good situation," says Carl Still, who runs the discipline center at Pullen.

"But if he's sent to the discipline center, I just give him the test and he doesn't have to worry about making it up."

Since the advent of court-ordered busing in January 1973, discipline has developed into an increasingly volatile issue in Prince George's schools. Black groups have complained that black students were being suspended from school in disproportionate numbers, while busing opponents have contended that busing was responsible for breakdowns in discipline.

In part, the idea for the discipline centers stemmed from attempts to resolve those issues, school officials said.

Assignments to the discipline centers are made by school principals and parents are always notified. So far, according to school officials, the program has won strong support from parents.

"They would much rather have their children on school property and under supervision than out roaming the streets," said Nabors. "And it's much better academically."