Washington — As the television camera pans in on two teen-agers apparently smoking marijuana in a school yard, the announcer speaks darkly of ''schools that don't teach'' and ''drugs and violence in the classroom.'' The scene is not one into which a parent would happily put his child.
And that is the message sponsors of the television ad are trying to relay to District of Columbia voters: Public schools are terrible, and parents need help so that their children can escape to private schools.
The TV spot is part of the most recent drive to win approval for tax credits for parents who send children to private schools. Next Tuesday voters in the District of Columbia will decide the fate of a proposal to allow up to $1,200 in tax credits for every child enrolled in a private or parochial school.
The plan is perhaps the most generous ever offered to parents, and it comes at a time when both the White House and members of Congress are giving verbal support to tuition tax credits. Still it faces an uphill battle in the District of Columbia, where virtually every public official, labor group, and public-interest organization staunchly opposes it. Even Roman Catholic Church officials remain neutral, although the plan would help parochial school parents.
Recent history indicates that voters elsewhere have not supported tax aid for nonpublic schools. In a dozen local and state referendums since 1966, not one such plan has won a majority. The most recent vote, which involved a plan to give students vouchers that they could spend at either a private or public school, lost 3 to 1 in Michigan in 1978.
Since then, the idea of giving parents tax credits has grown in popularity, especially among conservatives. President Reagan, in a telegram to a meeting of Catholic school administrators Oct. 17, again pledged his support for the idea. Government must ensure that ''all parents have the freedom to select for their children the formal education which they deem most beneficial,'' says the presidential message. At the same time, Mr. Reagan warned that a move for a federal tax credit will ''have to come later'' because of budget problems and must be phased in slowly.
A plan now awaiting action in the Senate would give parents from $250 up to a maximum $500 in tax credit for private school tuition, but it would cost the federal treasury several billion dollars and has been relegated to the back burner for now.
As a result, the District of Columbia vote Nov. 3 becomes a dress rehearsal for the congressional debate.
''We're trying to find a device to provide for revitalization of urban areas, '' says James Davidson, chairman of the National Taxpayers Union, sponsor of the tax credit initiative. The group, which claims more than 100,000 members nationwide, tried and failed to put a similar measure on the California ballot two years ago.
Mr. Davidson argues that with the tax credit, Washington will attract and keep middle-class residents who flee the public school system, which he calls ''rotten.'' The only way to force the public schools to improve, he maintains, is to give them more competition.
Ironically, the Taxpayers Union and its local group, the D.C. Committee for Improved Education, has little support among the wealthier white families who send their children to private schools. The proponents now are resting their case with black, moderate-income residents and parochial school parents.
Arnold F. Fege, director of governmental relations for the National PTA, sees the $1,200 tax tuition credit as disastrous. It would cost the city at least $40 million (supporters put the figure at $15 million), he says. Public schools would have to cut back programs, encouraging more parents to look for private schools. The better pupils would be ''skimmed off'' into private schools, he says.
Davidson concedes that the tax credit measure probably will lose at the polls next week. Should it win, his group still would face the inevitable challenge that tuition tax credits violate the constitutional separation of church and state by giving aid to parochial schools.