About 200 students at an alternative public high school in the District refused to attend classes yesterday to protest the principal's decision to place a popular social studies teacher on administrative leave for allegedly inciting students to circulate petitions calling for the principal's firing.

The students, who attend the School Without Walls, an academically rigorous school at 21st and G streets NW, met in front of the building yesterday morning, blocked traffic temporarily and listened to speeches.

Classes were canceled because of the protest, and several teachers stood on the steps in front of the school watching the demonstration.

David White, the teacher who was put on administrative leave Thursday by Principal Lydia Moss, also attended the rally and urged the students to exercise their "democratic right" to protest.

Wallace Southerland III, president of the school's student council, told the crowd of students that "Mr. White is more concerned about the students than he is about his job. It is his duty as a citizen and as a teacher to inform you of your rights."

In a letter to White, Moss, who came to the school last year, stated that he "deliberately incited students to protest . . . by encouraging them to sign petitions" urging that Moss be fired, and that he had made accusations that Moss was trying to close the school. Moss said that students and "an irate parent" complained to her about his alleged actions.

In an interview, Moss said, "Because this is a personnel matter, I really cannot comment more. We did meet with the students and tried to listen to their concerns, and hopefully some kind of resolution will come up next week. The majority of students have called for Mr. White to return to the school . . . . I'm only asking that the issues listed in her letter be investigated."

While on administrative leave, White will continue to be paid pending an investigation by the deputy superintendent of public schools.

The School Without Walls is an innovative school within the D.C. public school system that has an open enrollment and gives its students wide latitude to shape their curriculum.

White said that he asked students to write essays on several recent incidents at the school and that the assignments irritated Moss. White said the incidents included efforts by Moss to fire several teachers, stop the publication of a student publication and block the circulation of a survey prepared by students that assessed the quality of teaching in their school.

"There's a constant harassment from the principal," White said. " . . . Teachers who are trying to implement creative instructional programs at the school are not being supported. For instance, I want to create a social studies magazine and Mrs. Moss has tried to keep me from doing that."

Southerland said students rallied behind White because "he's a popular teacher and a good teacher. He wants us to learn how to think on our own and make our own decisions."

Gwendolyn Johnson, a sophomore who is in one of White's classes, said she joined the protest because, "We students don't know why Mr. White was put on administrative leave. We don't even know what administrative leave is . . . . Nobody wants to tell us what's going on. We want some explanations."