Representatives of Arlington's teachers have come out against Superintendent Arthur W. Gosling's plan to add a seventh period at the high school level next fall because, they say, it will shorten time for other courses and add to teachers' already heavy work load.

The Arlington Education Association, which represents about 95 percent of the county's 1,000 teachers, has asked that implementation of the plan be delayed for a year so that it can be redesigned with teachers involved in the process.

"We strongly support the concept of providing our high school students with the greatest choice of courses possible while maintaining quality instruction," AEA President Sara Jane Knight told the School Board this month. "The most serious flaws in the current proposal are timing and the total lack of teacher input."

"We're the ones that are going to have to carry this out successfully," Knight said later. "We were just told to plan for this."

Knight and other teacher representatives say the proposal is just one of a number of issues that prompted the education association last week to deliver a vote of no confidence in the superintendent and School Board.

But School Board member Dorothy Stambaugh defends the superintendent's proposal. She argues that the plan could offer students the chance to take more electives and at the same time help prevent teacher layoffs that might result from declining student enrollment.

"This is the year it has to be done if we're going to do it," she said.

Stambaugh argued that the plan would not add to the teacher work load and doubted whether shaving off minutes from other class periods to accommodate a seven-period day would have a significant negative impact on the current curriculum. She also questioned how much of a role teachers should have on new proposals at the planning stage.

The idea of a seven-period day grew out of parents and educators' concerns that students had less time for electives now that high school graduation requirements have increased from 18 to 20 credits.

In 1985, the School Board approved an optional seventh period for the county's three regular high schools that allowed students to take additional courses before and after normal school hours. But that program died this school year because of a lack of student interest.

Gosling proposed the seven-period day to the School Board in December and included $528,000 to fund the program when he presented his budget last month. "I think the seven-period day is a good idea," Gosling said. "It seems to me this is a financially advantageous time for us to do it."

School staff members, who say that senior high school enrollment will be down by about 440 students next fall, predict there will be a need for 28 fewer full-time positions in September.

Gosling has argued that implementing the seven-period day next fall would save about 17 full-time positions and describes the plan as "taking advantage of your opportunities."

Among recommendations for implementing the program is reducing the current 51-minute class to 47 minutes. Teachers have pointed out that such a move would shorten class time by almost three weeks a year. "At this point we can barely cover the curriculum we're supposed to," said Bobbie Whittier, a science teacher at Wakefield High School. "To reduce the time -- we would just not be able to cover the material."

Instructors, who teach five classes and have one period for planning time, also say they worry that the program would result in their having to prepare for and teach a sixth class. But school staff members say the program would give teachers an extra half-period for planning and a half-period in which they would be needed to monitor students in some way.

But teacher representatives say they are not convinced their work load would not be increased and argue that more time is needed to plan an effective program.

They have suggested that some teachers could be kept on next year to help put the program together.

"A full year to study existing models and to design the appropriate plan for each high school with meaningful teacher, parent and student input is an absolute necessity," Knight said.

The board is expected to act on the proposal Feb. 25 when it is scheduled to adopt the budget.