High school students at Riverdale Baptist School in Largo hone their computer skills by illustrating Bible verses on TRS-80 computer screens. Several miles away, seventh-graders at the small, virtually all-black Bethel Bible School learn grammar by punctuating the Psalms.

Teen-agers at Fairfax Baptist Academy, all of whom have pledged to "make a break" with rock music, are lectured in world history class on the evils of humanism. At National Christian Academy in Fort Washington, there are no high school history teachers, so Lawand Harley and her classmates work through stacks of packaged lessons, teaching themselves.

Studying alone in a cubicle, Harley, 16, fills in a blank in her history workbook: "The Nazis and Communists justified their acts of barbarism on the basis of . . ." She writes: "Darwinism."

The two dozen or so fundamentalist Christian schools in the Washington area vary widely in resources and approach, but their emphasis is the same: Bible, discipline and traditional values dominate every aspect of school life. To parents disenchanted with public schools, the idea of a Christian education for their children is an increasingly attractive alternative.

As a result, the fundamentalist schools are flourishing, and not just in the South or in rural areas. In the Washington suburbs, an estimated 6,000 students -- children of middle- and upper-middle class professionals and blue-collar workers -- attend the schools. Nationwide, the number of Christian schools has grown from several hundred in the 1960s to more than 10,000 today, with close to a million students enrolled. And the number of students is growing by nearly 80,000 a year.

"It's an explosive movement throughout the country, and it's increasing," said the Rev. Furlow Switzer, president of the Maryland Federation of Church Schools.

The increase in Christian schools has contributed significantly to the first nationwide increase in private school enrollment in several decades, according to federal officials.

In 1983, 12 percent of all students in grades one through 12 were enrolled in private schools, compared with 10.5 percent three years earlier, according to a federal Department of Education study. The study found that during the same period, Catholic school enrollment declined from 3.4 million to 3.2 million, and it supported claims by Christian school advocates that three new fundamentalist schools open each day.

The growth in fundamentalist schools is often traced to the Supreme Court's ban on prayer in schools in 1962, but enrollment also was boosted by the "white flight" that followed court-ordered busing to achieve integration in the early 1970s. In Prince George's County, for example, Christian school enrollment doubled after busing was ordered in 1973.

In recent years, however, Christian schools have attracted white and black students. The Maryland Association of Christian Schools reports that its 45 member schools have an average black enrollment of 17 percent. And there are several Christian schools in the Washington area with predominantly black enrollment.

Public school officials, while not ignoring the Christian school movement, deny that its growth reflects a failure of public education. They are skeptical about the lack of accreditation and teacher certification in many of the fundamentalist schools, and they point to the limited course offerings and narrow viewpoint offered to students.

But some educators see long-range implications for public schools.

"Public schools will continue to lose kids unless they recapture some moral imperatives in their teaching," said John Esty, president of the National Association of Independent Schools. "Public schools are making a great mistake if they do not realize a lot of noncrazy, nonright-wing parents still want some moral, ethical flavor."

That moral "flavor" is at the heart of the mission embraced by fundamentalist educators -- inculcating students with Bible-based morality amid the reading, writing and arithmetic.

Bible lessons are integrated into nearly every subject. Students often wear simple, modest uniforms, and some schools require their teachers to do the same. Rigid discipline is maintained, and punishment often entails spanking, which administrators believe is sanctioned in the Bible.

"The whole process of biblically spanking takes 20 minutes," said Fairfax Baptist administrator Gil Hansen, who applies no more than five swats with an 18-inch paddle. Then, he said, he prays with the student.

At Riverdale Baptist, where a new gym and spacious chapel with red velour pews reflect its status as one of the largest and wealthiest Christian schools in the Washington area, students must sign a yearly pledge that they will not smoke, drink or use drugs. But there are no complaints.

"I don't consider it being strict. It's not that bad," said Scott Tucker, a senior.

His schoolmates do not sport punk haircuts, but they otherwise look like typical teen-agers, with braces and painted fingernails. Some of them wear jackets embroidered, "Gymnasts for Jesus."

"I like the Christian atmosphere, being able to have devotions," said senior Karen Freeman, whose mother teaches fourth grade at the school.

Tommy Roberts, who has attended Riverdale for five years, said: "They demand more respect, more discipline. I think it will help us out later in life."

Some Christian schools require their students to swear off movie-going and rock music in addition to smoking and drinking. Rock culture, said Hansen, encourages sex, drugs and violence, and it "does more damage than any [other] single force."

Hansen believes it is this "drift among young people" toward drugs and "self-centeredness" that has alarmed parents and fueled the Christian school movement. "They're looking for something that will be an extension of their homes," he said.

To Christian school advocates, the public schools, historically imbued with mainstream Protestant values, have become overly secularlized. They also contend that drugs and violence are rampant in public schools, that discipline is lax and that academic standards have been abandoned.

"There is a basic conflict in world views that makes it impossible for parents to any longer keep their children in many of the government schools," said Jack Clayton, Washington representative for the American Association of Christian Schools. Public schools, he said, "brainwash children in humanistic values, which are entirely unacceptable to parents today."

Christian school educators argue that humanism -- a nontheistic philosophy that values human reason -- pervades the public school approach. And this "neutralization," or absence of religious foundation, they say, can be blamed for the lack of discipline and other problems.

But Christian school parents are more likely to cite atmosphere than the evils of humanism as their motivation for leaving public education.

For Betty and Earl Gearhart, the decision to enroll their 12-year-old daughter April in a Christian school came a year ago, after April's grades fell and she started getting in trouble at public school. Earl Gearhart, a construction representative for the federal government, and Betty took April out of Wakefield Forest Elementary School and sent her to Fairfax Baptist, where the tuition is $1,500 a year.

"Until the sixth grade, I was fairly pleased with Fairfax County schools," Betty Gearhart said. "But [April] ran into a couple of [bad] teachers and lost two years of education."

Betty Gearhart said she was shocked when April, who had always been a good student, received an "incomplete" in reading. And there were complaints about April's behavior. "She was wandering around the halls and they couldn't keep her in class," her mother said.

She is pleased with what she sees as a turnaround in her daughter since she switched schools. But Gearhart is angry because she believes that the public schools failed the family.

"We're middle income, and that portion of our salary that should be going to us is being taken to educate her, when our taxes are also going for that," she said.

Other parents, most of them middle-class, traditional families, say they were looking for better education and moral instruction when they chose Christian schools.

In December, James Mayer took his 16-year-old son Ralph out of Woodson High School in Fairfax and put him at Fairfax Baptist. "The attitude of both the teachers and the other students [at Woodson], the lack of respect, it was absolutely appalling," said Mayer.

Public school officials in the Washington area defend their systems and say they do not see the growth of Christian schools as posing a fundamental challenge.

"We haven't found it to be a threat," said George Hamel, spokesman for Fairfax County schools. Private school enrollment in that county, he said, is far below the national average, and the number of public school students is rising.

"We've always taken the position that competition is good," said Brian J. Porter, spokesman for Prince George's County schools.

"Yes, we have kids who are discipline problems," he added. "We have children who do not achieve well. But these problems exist throughout society. Public education is just that. It's for everybody." And if similar students from public and private schools were compared, he said, "we would come out head and shoulders above."

Like other public school educators, Porter questions the kind of quality control available in unaccredited schools that employ uncertified teachers. "Where's the checks, where's the balances?" he said.

Christian school administrators have generally avoided government certification, which they equate with state control of their church ministries. Most states, including Maryland and Virginia, do not regulate instruction in Christian schools, nor do they require teacher certification or accreditation. An exception is the District, where all nonpublic schools are required to meet instructional standards at least equivalent to those in D.C. public schools.

According to the Education Commission of the States, 16 states and the District regulate private schools. But in recent years, the trend has been to deregulate, with 10 states moving to less stringent standards.

Sometimes the instruction can be makeshift, supervised by parents in church basements in some cases, or by teachers without certification.

National Christian Academy in Fort Washington opened last year with 96 students, and it grew to 230 this year. It still cannot afford to hire a full complement of teachers, however, so its 25 high school students teach themselves with a set of workbooks that are part of a packaged curriculum known as Accelerated Christian Education (ACE).

Developed by a Texas minister, ACE has allowed churches and parents to open schools on shoestring budgets, without educational expertise or funds for teacher salaries. The system is used by only a few Christian schools in the Washington area, but extensively in the South.

In defending their academic standards, Christian school officials cite their students' performance on standardized tests. Riverdale Baptist, for example, where students below grade level are not admitted, reports its students average in the 79th percentile on the California Achievement Tests. That compares to a 55-56th percentile average last year for public school students in Prince George's County, according to Elwood L. Loh, testing supervisor for the county schools.

"We serve two different clientele," Loh said of the comparison between the county schools and Riverdale. "They serve a very select clientele."

Researchers confirm that Christian school students generally fare well on standardized tests. But one educator who has studied Christian education has found it lacking in the "richness of instructional life."

The first priority in Christian schools is spirituality, said Alan Peshkin, a University of Illinois professor who spent 18 months as a participant-observer in a midwestern Christian school. "That takes away from focusing on other educational concerns," he said. "They close off alternative views."

The obvious example is the evolution-versus-creationism debate. While many fundamentalist schools will acquaint their students with evolution, they also teach that the theory is incorrect.

"I don't leave them hanging," said Kelly Schultz, a high school science teacher at Riverdale Baptist. "When they leave, they know how I stand. I take a very narrow viewpoint, but I do explain the thought processes" behind evolution and other opposing theories.

The religious overtones that permeate the instruction, Peshkin said, put Christian schools in the role of vocational schools. "What happens every day, class after class, year after year," he said, "is that students are being oriented to think the single most important occupation is full-time Christian service."