The Montgomery County Board of Education unanimously agreed last night to advance by one year the closing of Charles W. Woodward High School in Rockville. Woodward's ninth graders will go to Walter Johnson High School this fall, and the two schools will be consolidated at Walter Johnson in 1987 instead of 1988.

Michael Farrar, a Woodward parent and community leader, called the vote "a charade," contending that board members had made up their minds to move up the consolidation before last night's public meeting.

Rob Bernstein, Woodward PTA president, said the stepped-up consolidation will be "a disaster" because of hostility between the two student bodies and crowding. "You take those hostilities, throw them into a crowded situation where students are stumbling over each other to get to class and the level of friction is going to be such that I would be concerned for the safety and welfare of the students," Bernstein said.

Woodward parents and students have withdrawn from a committee set up to plan a smooth transition because they say their recommendations are being ignored, among them who should be the new principal of the combined school.

Walter Johnson parents generally support the speeded-up schedule as do several other PTAs in the community.

Board members defended their decision to move up the consolidation because all students will get more class offerings and the school system will save about $500,000 a year in operating costs.

The board voted last November to operate the two schools as a split campus in 1987-88, with students shuttling between them. The following year, 1988-89, Woodward would have been closed and all its students sent to Walter Johnson. The reason for the consolidation, school officials have said, is declining enrollments at both schools.

Woodward parents and community leaders hired a Baltimore law firm and appealed to the State Board of Education. As a result, a state hearing examiner recommended last month upholding the decision to close the school but objected to the split campus plan. He said the split campus proposal was "arbitrary and unreasonable" because school board members had not given community leaders an opportunity to comment on it or explained how it would work.

The state board is expected to issue its final ruling on the Woodward case May 27.

The plans to speed up the merger by one year were announced by Montgomery School Superintendent Wilmer S. Cody several weeks ago. Cody's plan will add 10 portable classrooms to Walter Johnson in 1987 and renovate seven unused classrooms to accommodate the additional Woodward students.