Fairfax County School Superintendent Robert R. Spillane unveiled a $5.6 million plan last night that would end the longstanding practice of closing elementary schools two to 2 1/2 hours early on Mondays, beginning next fall.

Under the proposal, nearly 70,000 elementary students would attend school for 6 1/2 hours Mondays, just as they do Tuesdays through Fridays. The additional class time would be devoted to core subjects such as English, mathematics, science and social sciences. Kindergartners would have a uniform three-hour day and would for the first time have separate music and gym classes.

Spillane suggested paying for the changes from a $7 million reserve set aside by the School Board last summer in anticipation of budgetary shortfalls next year.

The board will hold a public hearing Nov. 13 and vote Nov. 15.

While School Board Chairman Kohann K. Whitney and several other board members cautiously embraced it, the plan was assailed by union leaders who said it would rob teachers of collaborative planning time they now enjoy on Monday afternoons.

In making his proposal, Spillane dramatically scaled back a $13.4 million version produced last month by a committee of teachers, parents and principals. The superintendent cited the expense in a time of gloomy fiscal projections.

Last month's committee plan would have hired more than twice as many teachers -- 317 compared with 129 -- and devoted more time to art, music and physical education, ensuring homeroom teachers the time to plan lessons jointly.

"Anything short of that will guarantee an unmitigated instructional disaster," warned Maureen Daniels, president of the 6,800-member Fairfax Education Association, which endorsed the committee plan. "This report is an all-or-nothing proposition. If you can't afford to do it right, don't do it."

Mark Glofka, vice president of the 1,200-member Fairfax County Federation of Teachers, said the plan would reduce teachers to "babysitters" because they would not have time to plan lessons. "Doing without early closing is like playing 60 minutes of football without a huddle," he said.

Spillane said his plan does ensure that teachers have as much planning time during the week by hiring new teachers to take over their art and physical education instruction. Union leaders, however, complained that teachers would not be able to work together as they do now on Mondays.

Any change on a Monday is resoundingly opposed by rank-and-file classroom teachers. At a meeting of 250 teachers last month, Spillane asked for a show of hands from those who supported eliminating early closings. No hand went up.

Likewise, there has been little support from parents and community leaders. Most PTAs were vigorously opposed or were divided last year when the proposal was last raised.

The School Board, hoping to increase instructional time for students and ease day-care problems for parents, approved the schedule change in concept last November, but postponed it for a year because of the cost and community opposition. Now, with budget outlooks far grimmer and principals preparing to cut money for textbooks and other supplies, the once-unanimous board support seems more shaky.

Board member Carla M. Yock (Mason) articulated the problem in a recent interview.

"If people aren't crying for it and it's going to cost money and I'm representing the people, it's very hard for me to support it," said Yock, a former teacher and current assistant principal in another county. "Professionally, it's easy to support it because I know it's the right thing to do, but that's not what I'm paid to do. I'm paid to represent my constituents."