The Arlington School Board asked Superintendent Charles E. Nunely last night to prepare at least five plans keyed to two grade groupings that the board may want to implement when it begins closing schools in 1984.

In a motion offered by Chairman Evelyn Reid Syphax and adopted unanimously, the board narrowed its preferred grade configurations to two formats and asked that two or more options for using school facilities be developed for each that would maintain:

* The current system, known as the 6-2-4, in which children in kindergarten through sixth grade are grouped in elementary schools, grades seven and eight in intermediate schools, and nine through 12 in high schools.

* A variation, known as the K-7 and 8-12, in which pupils in kindergarten through seventh grade would be grouped in elementary or intermediate schools and those in grades eight through 12 in high schools.

Although the current system would most likely result in the closing of one of the county's three regular high schools and possibly two of the four intermediate schools, the board left Nunely leeway to present options that would leave all those schools open.

The board also asked that the plan permit as many neighborhood elementary schools to stay open as feasible and agreed to keep the county's three alternative school programs, each of which stresses a different educational philosophy.

Nunely is expected to report back to the board in January. Syphax's motion asked that the options take into account racial and ethnic balance, population trends, student performances, programs of study and community sentiment.