Wilmer S. Cody spent June 30, his last day as Montgomery County's school superintendent, completing a long memo about plans to improve student test scores. The next morning he began what he calls a sabbatical, although it is not too different from what he had been doing.

Cody is heading a yearlong project for the Council of Chief State School Officers here to come up with ways to assess student mathematics skills state by state. Funding by the National Science Foundation and the U.S. Department of Education was recently approved for the project, which is to result in recommendations about what knowledge and skills to test and how to report the findings.

The congressionally mandated National Assessment of Educational Progress has resulted over the years in trend studies called "A Nation's Report Card" of such issues as writing skills and minority achievement.

Cody, 50, who lives in Chevy Chase, headed the Montgomery County school system for four years. He says the appointment is giving him a break from school work while he thinks about what he would like to do next: "probably return to an administrative position somewhere."

This year, Cody was one of three finalists for school superintendent in his native Mobile, Ala., where he had been a teacher and principal. He withdrew his application when he learned that the school board had signed a consent decree in a textbook banning case brought by a group of Mobile parents opposed to the teaching of secular humanism. The plaintiffs, whose initial victory in the case was later overturned, have appealed to the Supreme Court.