Three Northern Virginia school boards criticized proposed new state requirements for a ninth-grade literacy test and reduced class sizes last night at a public hearing that offered a preview of next session's debate in the Virginia General Assembly.

The state Board of Education hearing was called to hear comments on changes in the "standards of quality" for all Virginia schools for the 1988-89 school year. The changes also would require remedial programs such as summer school for low-scoring students and would require the state to mandate improvements in "educationally deficient" schools.

The state board approved the changes when it voted in June to impose new accreditation standards, and is likely to approve them again in a vote on the standards of quality in October. But the last word will come from the legislature when it meets in January, because lawmakers have the power to change the standards or refuse to finance them.

"People opposing what we've said will no doubt be heard again in the General Assembly," said former state senator Adelard Brault, one of two state Board of Education members attending the hearing at Francis Hammond Junior High in Alexandria, where only eight speakers offered testimony. It was one of five sessions held around the state.

One of the most attention-getting changes proposed by the board -- requiring students to take a literacy test as early as the sixth grade and pass it in order to enter ninth grade -- was questioned by two local school boards. Fairfax County School Board member Laura McDowall and Alexandria School Board member Judith Seltz said the test may be unfair to students from non-English-speaking families.

"Holding these students in the eighth grade until they pass the literacy test would create insurmountable problems and solve none," Seltz said.

The Fairfax and Prince William County school boards also questioned requirements for reduced class sizes in the first grade, and in middle and high school English classes.

Fairfax County officials estimate the requirement could cost the county more than $1.8 million in additional teacher salaries, and urged the state to provide the additional money if it imposes the requirement.

In space-squeezed Prince William County, where population is growing so fast that 35 classroom trailers were added this year, "we just do not have any place to put" additional teachers, Robert Jozwiak, the school system's supervisor of testing and accreditation, said in opposing the requirement for smaller classes.

The Fairfax and Prince William representatives also opposed a potential requirement for summer school for students with low test scores.