PUBLIC SCHOOL TEXTBOOKS always have been America's political weather vane. They pointed up the Red Menace in the '50s, switched to "relevance" for the '60s, and finished out the '70s with minority complaints and women's liberation.

But in the '80s, the wind is once again blowing from the right. Across the country, the sins of communism and godlessness are being invoked as reasons to ban books. As a result, schoolbooks are being rewritten once more -- this time to conservative specifications. In biology, the Biblical story of creation is given equal pace with the theory of evolution. In literature, editors are careful to remove "offensive" language. Stories about conflicts between parents and children are avoided because they might undermine parental authority. Teachers' manuals stress that teachers should not challenge the values of students, nor invade their privacy. And social studies publishers revise their histories in an attempt to mute criticism that they are presenting communist propaganda.

Publishers admit that they are feeling the pressure. Paula Hartz, an editor at Holt, Rinehart and Winston, says, "It's getting harder and harder . . . . We're trying to second guess in advance what people are going to complain about. Often you guess wrong." The reaction in the industry is to shy away from controversy. "We certainly see the handwriting on the wall," Hartz says. "Textbooks are becoming more conservative."

One indicator of the growing discontent with schoolbooks is apparent from the number of censorship incidents reported to the American Library Association. Judith Krug of the ALA reported that the number of complaints about attempted censorship four years ago was 300, the highest since the height of the McCarthy ear. Ninety percent of those complaints came from schools. Since Ronald Reagan's election, Krug says, complaints have grown five-fold: from three to five calls a week to three to five a day.

During most of the 1970s, the strongest pressure came from the left -- from blacks and women who demanded fairer treatment in textbooks and school library books. Although much of the criticism was justified, a few demands were silly: In California , for example, Dr. Doolittle and Mary Poppins were called racist and sexist.

But recently, criticism about textbooks has been coming from the political right. Edward Jenkinson, who has been monitoring censorship for the National Council of Teachers of English for years, began noticing the trend when reports from school systems across the country told of new groups who were challenging what was being taught in school. Led by religious fundamentalists and conservative political activists like Phyllis Schlafly, these groups charged that many textbooks taught immorality, invaded parents' privacy, promoted promiscuity and drug abuse, and proselytized a communistic world government. They went on to fight against the offending books at both local and state levels. They have succeeded in having many titles withdrawn from state-approved textbook lists.

In Montgomery County, the school system spent more than $75,000 a few years ago fighting a suit containing most of these charges lodged by a group called Parents Who Care. As a result of the suit, many textbooks, primarily for health courses, were revised or eliminated, and county educators became "very, very careful about our procedures," says Nancy Walker, director of the county's instructional resources department. Walker believes the suit was instrumental in getting the school board to return to a much more structured curriculum.

In many school systems across the country, hundreds of books have been removed from school libraries, including works by Shakespeare and Mark Twain and books by and about blacks and women. In at least two places -- namely Warsaw, Indiana, and Kanawha County, West Virginia -- schoolbooks have actually been burned. "People are walking into school systems and libraries and maintaining they have a mandate from the election to clean up America," said Jenkinson, who gets calls from beleaguered educators who want help. In some school disricts, he says, individual teachers have been singled out in public meetings as "instruments of the devil." "Let me tell you," Jenkinson says, "I'm scared."

Jenkinson and other educators point to the Rev. Jerry Falwell, head of the Moral Majority spokesman, says that's just not true. "We're against censorship and against it and against it." Although his organization does insist that concerned parents have a right to influence the schoolbooks which their children are using, he adds, "We admonish them to be polite, use good etiquette . . . and to go through channels. We flatly forbid our people from being involved in any kind of personal attack," Godwin says.

The Moral Majority does, however, alert its members to books which should be looked at carefully. Most recently, the group sent letters to more than 400,000 members which criticized a health textbook by Ramdon House and a popular resource book in junior and senior high schools, Our Bodies, Our Selves. Paragraphs from the latter were reprinted in the letter, which quoted one passage as reading: "If you have never masturbated we invite you to try." Godwin says this is "very, very offensive" material which parents ought to be aware of.

The controversy over textbooks is likely to grow in coming months when a conservative contingent in Congress, led by Sen. Roger Jepsen (R-Iowa), introduces a bill known as the Family Protection Act. The legislation will address a host of right-wing concerns from prayer in the schools to whether declared homosexuals should be protected from employment discrimination. A similar bill introduced last year, but never acted on, would have made it unlawful to prohibit parental review of textbooks and prohibited the use of federal funds for the purchase of textbooks and other educational materials that denigrate the traditional roles of women. Jepson is now revising this previous proposal for reintroduction. It i sure to attract the support of key senators such as Paul Laxalt (R-Nev.) and Orrin G. Hatch (R-Utah), who pushed for similar legislation last year.

Such congressional intervention has caused alarm in the publishing industry.

"We are aware of the [Family Protection Act], and we are concerned," said Richard Kleeman, vice president of the American Association of Publishers. r"I think there are some dangerous and censorious parts to it . . . . You just cannot write textbooks by legislation."

Such pressure on the $850-million-a-year publishing industry has resulted in more self-censorship. "You make whatever concessions are necessary to do what good you can," said Holt, Rinehart's Paula Hartz. "A book that doesn't get into the hands of kids just doesn't do any good."

Selling textbooks has become more difficult each year, publishers say. One reading series can take as long as five years to develop and cost anywhere from $3 million to $10 million, money which must be invested up front. Textbooks don't begin to earn a profit until they are on the market for two or three years. Because they are so expensive to produce, profits depend on large sales. "Our money is made on volume," said Hartz. "We can't afford to take chances."

Textbooks have to be accepted by state review boards and local school districts, many of which have conflicting standards. These boards frequently demand changes which cost between $300 and $500 a page -- an incentive for publishers to print textbooks that won't need any changes.

Two key states for textbook sales are Texas and California, the rock and the hard place for the publishing industry. In Texas are Mel and Norma Gabler, a conservative couple responsible for banning from use in the schools tens of books, including five dictionaries, which contained "improper" language and values. In California, there are strict state requirements for "fair" textbook treatment of blacks, women and minorities. "If you go through both," Hartz says, "You can pass anything."

Much of what is appearing -- or not appearing -- in textbooks these days is because of the Gablers' work. The couple, who run a nonprofit group called Educational Research Analysts in Longview, Texas, read every new textbook published. They then send their reviews to parent groups in each of the 50 states. Also the Gablers make hundreds of challenge at the state textbook adoption hearings in Austin each year. Of the 28 textbooks opposed by them last year, Texas rejected 18, according to Newsweek.

In addition, because of the protest in Texas, Shirley Jackson's classic story, "The Lottery," was dropped from four anthologies. In another incident, a Ginn junior-high reading series drew 163 objections from the Gablers, for among other things portraying Robin Hood as a folk hero. The Gablers' reviews cause fear in the publishing industry. "The Gabler have taken the word 'inquiry' and have made it dirty," said Richard Carroll, president of Allyn & Bacon Publishers.

Despite often sharp criticism, the Gablers' influence continues to spread. Their reviews are used by groups in hundreds of school systems to challenge textbooks, and they have the support of activist, political groups such as the Moral Majority. Their self-styled brand of textbook review is beginning to catch on. In North Carolina, the Rev. Lamar Mooneyham, state chairman of the ymoral Majority, has launched his own textbook committee and in Alabama a group of parents succeeded in removing five social studies textbooks from the state list because they "denied the deity of God and promoted secular humanism."

One of those books was Unfinished Journey, a social studies textbook published by Houghton Mifflin. A spokesman for the company said that Houhton Mifflin was "concerned and troubled" by the Alabama decision. "We have brought the best of scholarship and accumulated editorial experience of many years to the task of developing s accurate and objective a book as we can possibly publish," the spokesman said, "and we continue to believe, as do its many users across the nation, that it is a sound publication, fair to one and all."

Despite Houghton Mifflin's defense of its product, the fact that it and hundreds of other books now are being challenged is having a chilling effect within the industry an inside the classroom.

"sometimes I feel there should be no controversy in what I teach," said one exhausted Chevy Chase, Maryland, elementary school teacher, "and that's scary." Mark Twain's Huckleberry Finn was removed from Montgomery County classrooms for being racist, he complained along with an "excellent" reading series that was considered sexist. In addition, the list of banned textbooks was greatly lengthened by the Parents Who Care suit. "When each group gets done taking out their biases," the teacher said, "I don't know what's going to be left."