Peter Robertson, a junior at Charles W. Woodward High School in Rockville, has been elected to the student seat on the Montgomery County school board.

Robertson, 16, last week defeated Churchill High School junior Louise Williams to become the sixth student to sit on the Montgomery board.

As the student representative on the seven-member board, Robertson will have no formal voting power, but will serve as the conveyor of student sentiment on various issues before the board. Among the most important school items Robertson will face as a board member will be proposed changes in high school graduation requirements.

Over the years, the influence of the student member of the Montgomery board has vacillated as the political hue of various boards has changed.

Jonathan Lipson, the student member two years ago, frequently was at odds with the conservative board majority over school closings that involved race and was an advocate of a more liberal approach to racial and educational issues.

This year, student board member Kurt Hirsch has sided regularly with the newly elected five-member majority and, as a reflection of the more receptive approach, has been invited to attend a number of executive board sessions, which generally are not open to the student member.

Earlier this year, two of the newly elected board members voted to support changes in state law that would have given the student member voting powers. The legislation failed.