Seven of the 11 seats on the Washington board of education are up for grabs in Tuesday's election, and 18 candidates are competing for them.

Voters throughout the city will fill two at-large seats, including one being vacated by board president Therman Evans.

In addition, board representatives are being chosen in five of the city's eight wards. In Wards 2, 3 and 8, the contests are for regular four-year terms.In Ward 4 and 7, candidates are competing to fill two-year terms because members elected two years ago have resigned.

Although the school board no longer is at the center of the political spotlight, many of the campaigns have been lively. The issue is most of the ward races has been which candidate can be more effective, rather than sharp differences in policy. Most of those running have warm praise for superintendent Vicent Reed, who for the past two years has led the school system through its most stable time in a decade.

Reed replaced Barbara Sizemore, who was fired by the board in October 1975 after a protracted controversy. During the eight years before Reed took office, District schools had four superintendents.

Only two of the board members who took part in the Sizemore controversy are seeking reelection. Board vice president Carol Schwartz, who tells campaign audiences that she is proud to have helped fire Sizemore, is seeking a second term in Ward 3. Barbara Lett Simmons, who was Sizemore's most vigorous supporter on the board, is running for reelection at-large.

Although she rarely mentions Sizemore directly, Simmons emphasizes her support for two of the former superintendent's chief programs - decentralization and innovative schools. In addition, Sizemore has contributed to her campaign. Simmons speaks cooly about superintendent Reed's competency-based curriculum, which is designed to develop a uniform step-by-step teaching method throughout the school system.

Simmons also has spoken pointedly about being the only black candidate in the at-large contest and has warned that the D.C. school board might be "dominated" by whites. At present the board has eight black members and three whites. No matter how Tuesday's election comes out, the number of blacks can only drop to seven.

Besides Simmons, a former teacher who heds an educational consulting firm, the other three at-large candidate are:

Afrodita Constantinidis, a representative of the Socialist Workers Party, who charges that the present board has tried to "please white business interests," and urges that the curriculum emphasize the "oppression and abuse of blacks, Latinos and working people."

Stuart Rosenblatt, director of the Washington local office of the U.S. Labor Party, who has called for a moratorium on city debt repayments as a way to boost school spending, and has urged more emphasis on science and the classics of western culture and an end to any teaching about "environmentalism" or homosexuality.

Frank Shaffer-Corona, an activist in loca Hispanic groups who strongly supports Reed's competency-based curriculum and calls for discipline and promotion standards coupled with "care and respect."

In Ward 2, Alverta Munlyn, an educational specialist for the Center City Community Corporation, an anti-poverty group, faces Alaire Reiffel, president of the Ross School PTA and a lawyer, Munlyn has been endorsed by the Ward 2 representative on the D.C. City Council, John Wilson, while Rieffel is backed by the ward's current school board representative. William Treanor, who soundly defeated Munlyn four years ago.

In Ward 3, Schwartz, a former teacher, is being challenged by Kenneth T. Lange, a lawyer for the Washington Area Council on Alcoholism and Drug Abuse, and Gwendoline G. Reiss, a real estate agent who ran unsuccessfully for the same seat in 1973. The contest has roused considerable heat, Reiss has sued unsuccessfully to get Schwartz's name taken off the ballot. Schwartz has charged Lange with listing some of her supporters as favoring him in campaign literature.

In Ward 4, incumbent Victoria T. Street, a retired teacher appointed to fill the vacancy last summer when Hilda Mason was elected to the City Council, will be trying to win in her own right. Her two opponents are Gilbert A. Diggs, a former regional superintendent, and Philip E. Pannell, a community outreach worker for the Howard University Center for Sickle Cell disease. Pannell is president of the D.C. Young Democrats, and ran unsuccessfully for the board in 1975.

Street has received strong backing from Ward 4 Council member Arrington Dixon.

Minne S. Woodson, a retired teacher appointed to the board last January, is running for the Ward 7 seat against Rufus (Catfish) Mayfield, a program host on WOOK radio and emcee of entertainment shows, and Gloria J. Anderson, a program coordinator for Anacostians Concerned for Senior Citizens. Anderson is being backed by Ward 7 Council member Willie J. Hardy, who clashed with Woodson last spring over the appointment of a regional superintendent for her area.

The candidates for Ward 8 are Genevieve B. Artis, a social worker for the Anacostia preschool program; R. Calvin Lockridge, a former director fo the Response to Educational Needs project in Anacostia and member of the D.C. Democratic state committee; and Wilbert Williams, a lawyer who works for the Department of Agriculture as an equal opportunity specialist. The ward now is represented on the school board by Julius Hobson Jr., who decided not to seek reelection and is backing Artis. The Council member from the ward, Wilbelmina Rolark, has endorsed Lockridge.

Besides filling the seven school board seats in Tuesday's election, Washington voters will select members of advisory neighborhood commissions. Also on the ballot will be proposals to change the city charter to permit the recall of elected officials and to allow voters to place initative and referendum question on the ballot. The polls will be open from 7 a.m. to 8 p.m.