The D.C. school board voted last night to restrict all elementary, middle and junior high students to school grounds from 9 a.m. to 3 p.m., a measure that school board members said is intended to improve safety and curb student drug activity during school hours.

The new measure is scheduled to take effect in September after a committee to be appointed by Superintendent Floretta D. McKenzie works out details to implement and enforce the new policy. Currently, most junior high students are permitted to leave school grounds during the day -- primarily lunch hours -- but under the planned restrictions, they will be able to do so only if a request from their parents is approved in advance.

A recommendation that would have restricted high school students to school grounds was brought before the board last fall but was sent back to committee where it was killed after parents, teachers and administrators opposed such restrictions.

"I agree wholeheartedly with the restrictions on the elementary school level," said Camilla C. McKinney, the lone student representative on the board, "but I expect some junior high school students will be upset."

Eugene Kinlow (At Large), chairman of the committee that recommended the new restrictions, said he hopes students will view this measure positively because "it is for their own good."

"Some students leave school during lunch and never come back, others return late," Kinlow said. "Some students are distracted by mischief and get in trouble with the law.

"Many of students drop out of school during junior high school," he said. "We hope to protect the students from outside distractions."

Board member Edna Frazier-Cromwell (Ward 1) said the restrictions will help curtail drug use by the students. "There has been an increase of drug abuse around our schools," she said. "Perhaps this is just one measure we can take to better supervise our students during school hours."