The Prince George's County Board of Education completed steps last night to expand its six-month-old magnet school plan, unanimously approving a proposal to provide new programs and resources for Dodge Park Elementary School by designating it a compensatory school.

The board's decision on the Landover school put the final touch on plans to accelerate the magnet program implemented last fall as a means of encouraging desegregation. The bulk of the expansion, calling for 21 new magnet programs by the 1987-88 school year, was approved two weeks ago.

The expansion of the magnet program, proposed by Superintendent John A. Murphy last month as the second phase of the plan, also accelerated the timetable originally proposed in 1985, implementing the rest of the program in two instead of three years. The magnet program offers special programs to draw students outside their neighborhoods as a means of integrating schools.

When the board voted initially to expand the program two weeks ago, the lone negative vote was cast by board member Barbara Martin, whose proposal to make Dodge Park Elementary a compensatory school had been deferred for more study.

Compensatory education schools have predominantly black enrollments and are given additional resources because officials say their distance from predominantly white schools makes them impossible to desegregate.

Martin, whose district includes Dodge Park Elementary, said many parents opposed Murphy's original plan to make Dodge Park a magnet school, with about 300 students bused to two other schools.

Under the plan approved last night, Dodge Park Elementary will operate beginning in the fall with classes for kindergarten through fourth grade. Fifth and sixth graders will be reassigned to Robert Goddard Middle School, where they will receive extra staffing while in those grades. They will remain at Goddard through the eighth grade.

In addition to Dodge Park, five other compensatory schools will be created. Five schools will be closed under the plan.

The board also decided last night to study ways to phase out "open lunch" at Suitland High School, a program that allows students to leave campus during lunch time. Only two other county high schools -- Laurel and Bowie -- have open lunch programs.

Also last night, Murphy said that more than 500 persons have applied for teaching jobs since the announcement last week by county business leaders of a package of incentives aimed at making Prince George's more competitive in recruiting teachers.