VELLA BARNETT SILVER, 77, remembers the principal at the elementary school where she taught urging her staff, "Keep growing!

Don't become stagnant!" Silver is still taking the advice to heart. "It's no fun staying home and doing nothing," she says. "What's the sense of shriveling up as you get older? It's so boring just looking at the four walls."

Silver is one of 80,000 people over 60 who participated in Elderhostels in 1984, one of the increasingly varied educational programs for the elderly offered by universities, community colleges, senior centers, libraries and other institutions throughout the United States and abroad. In 1981, 768,000 people over the age of 65 participated in adult education, according to the National Center for Education Statistics.

Choices open toolder citizens include: Elderhostels; a humanities program sponsored by the National Council on the Aging; and Institutes for Learning in Retirement held at several universities. About three quarters of the states also allow seniors to take state university courses at reduced or no tuition if space is available.

This growth in educational opportunities "is related to a larger trend that suggests things are getting a little better for older people," says Harry R. Moody, deputy director of the Brookdale Center on Aging at Hunter College. He feels that for many of the elderly reduced economic pressures mean they "can start thinking about the positive end of the spectrum and ask themselves, 'What more is there to life? How can I keep growing as a person?'"

He adds that it is seniors who seem to be living out the values of the '60s. "If you look at college students today, they're very grim and determined. It's people like those in senior programs who are in a way living the counterculture life, with the means and the leisure to pursue their own interests and self development." %Variety Is the Spice

IF SENIORS choose Elderhostels, they might be studying Thomas Jefferson's views on American education at the University of Virginia, or living in tepees, eating vegetarian meals and taking solar showers as they learn Aikido at the Windstar Foundation, an environmental research center in Colorado.

Elderhostels is perhaps the best known of all the senior educational programs. It is a network of more than 800 colleges, universities, private schools and other educational sites offering full accommodation and short- term, usually one-week courses in a remarkably broad range of liberal arts and science subjects to people over 60. Founder Marty Knowlton modeled the concept after youth hostels in Europe, where he spent four years on a walking tour when he was in his early fifties. With his friend David Bianco, director of residential life at the University of New Hampshire, he devised a program where seniors could combine travel, a series of convenient, inexpensive accommodations and the intellectual and cultural benefits of an academic setting. Many participants go from one course to another throughout the summer, with choices in the United States, Canada, and several other countries. Courses are also offered during the academic year.

Elderhostels started only 10 years ago with 200 students at five locations in New Hampshire, and "we had to club them over the head and grab them to get them there," says Cady Goldfield, Elderhostel's director of public relations, because at the time no one knew exactly how the program would work. By 1976, 2,000 adventurous hostelers had signed up, and nearly 5,000 in 1977. This year 100,000 are expected to participate.

"It's an idea whose time has come," says William Egelhoff of the Virginia Center on Aging at Virginia Commonwealth University, the director for Virginia and D.C. Elderhostels. "Today's elderly are better educated, more affluent, more widely traveled, and more receptive than any generation of elderly in the history of this country. And for them, Elderhostels fills a real need. It combines learning with travel, both of which seem to suit them."

The senior participants are enthusiastic, energetic, adventurous, physically active, belying the myths about aging. "They're looking for activities, exercise, health, smiles, laughing," says Niccola Bojanowski, Maryland State director and assistant dean at Johns Hopkins' Peabody School of Music, which hosts an Elderhostel program. 'Sixty to 70 percent of the people who reach Peabody are retired professionals; most of the women have worked. We have to provide transportation so that they can get to the campus to do their jogging and their early swim, and evening tennis is popular."

If age is a factor, it is only because they have an even keener interest in the subjects they study than they did when they were younger. "We don't teach things that have to do with aging," Goldfield explains. "We provide actual educational experiences for people who are sixty and over, without pointing out the fact that they are over sixty."

Thus at Peabody this summer Elderhostelers can study Chopin, the Romantic heritage in visual arts, the tradition of square dancing, or learn to play the recorder. Virginia programs include "Perspectives on the Civil War" at Virginia Commonwealth University, ending with a field trip that follows Lee's retreat from Petersburg to Appomattox. Keystone Science School in Colorado offers an ecology program which will take Elderhostelers backpacking in the summer and cross- country skiing in the winter.

Kentucky offers several camper programs where seniors stay in their own recreational vehicles at nearby campgrounds and colleges provide transportation to and from campuses. The seniors who attend "are even more adventuresome, flexible and adle than the typical Elderhostelers," says Alice Brown, Kentucky's director. At Georgetown College this fall, campers can participate in "The Festival of the Horse," which celebrates the traditions of bluegrass throughbred country and provides information on riding, breeding, and the economy of the horse industry.

Last year about 1,600 Americans also attended Canadian programs, according to Katharine Rice, Elderhostel director of Canada's Atlantic region, who points out that "September is a particularly gorgeous time of year here and the salmon fishing is fantastic." Participants can study Cape Breton architecture, the history of Newfoundland at Bay St. George, or the flora and fauna of Labrador at Churchill River, among many programs featuring local geography or heritage.

These programs reflect another aspect of Elderhostel courses, to represent the traditions, local and regional interests, or particular strengths of the hosting institutions. Gallaudet's Elderhostel program, for example, offers courses in art history and visual theater for deaf elderly people fluent in sign language. They also run a popular program for those who have developed hearing impairments in their later years, which, although it deals with an aspect of aging, is included because it draws on Gallaudet's specific expertise.

Dr. Harriet Kaplan, an audiologist who teaches in the Gallaudet program, feels that interaction with spouses and family members who share the benefits of information and counseling, with faculty, and with other Elderhostelers in similar situations is a special benefit of the course. She moves into the dorms to participate more fully, and by the end of the week feels that "the group has become very cohesive, and permanent friendships form." Education as Social Life

THE SOCIAL aspect is a valued part of all senior educational programs. As in undergraduate days, getting to know people with different points of view and sharing experiences are stimulating and enriching. Murray Wernick, 67, a retired federal economist who has attended eight Elderhostels with his wife Marie, says he especially enjoys meeting many people who come back year after year; their shared experiences and expectations "make it a kind of congenial group, a fellowship."

For older people who have a tendency to be isolated through lack of confidence, physical limitations, or their own and society's stereotypes of age, this socialization can be even more important than it is for a student at 18. "Participants say how valuable it is to meet with people of similar interests who are very committed to the learning process," says Martha Hoyer, director of Colorado Elderhostels. "They weren't aware that people in this age group are still interested in education."

Continuing education "tends to mobilize people and gets them active and interested in what's going on in their communities," according to Ron Manheimer, director of the National Council on the Aging's humanities program. Since 1976 more than 1,200 groups, with 25,000 people per year, have participated in eight-week sessions sponsored by the Council at senior centers, libraries, museums and other community locations. Groups can choose from 12 packages including readings, questions and ideas for studying themes from American history and culture, ranging from Americans on the land, to the way history has affected family life, to the issues of the day reflected in Broadway musicals.

Manheimer feels the program helps those "who have lived a part of American history come to terms with the events that shaped their experiences and place them in a broader context. It also introduces them to a multiplicity of viewpoints and enables them to see commonalities. Both these aspects give them the freedom to reinterpret what has gone on in their lives."

For many seniors, educational programs provide opportunities not only to evaluate and make sense of their past, but to assess where they are right now in their lives. Often the confidence they gain by analyzing materials and contributing to discussions helps them to recognize their abilities and talents and realize the validity of their experiences. With this confidence, "they suddenly feel a sense of responsibility to pass what they know on to younger generations or other older people like themselves," says Manheimer. Many of the humanities program participants go on to lead other groups.

At the Institute for Learning in Retirement at American University, most of the study group leaders are also seniors, either emeritus faculty or retired professionals. The Institute is a unique membership organization where seniors elect a council which helps decide topics to be offered, and pay a set fee which allows them to participate in up to four study groups each semester. Programs with a similar format also operate at more than 20 universities, including UCLA, Duke, Harvard, and the New School, where the concept originated. In its third year at AU, the Institute has 275 members. Classes rely on peer participation, where members do both learning and teaching. Sharing Their Knowledge

IN ALL THESE programs faculty say they are delighted by the amount they learn from older students and their evident enthusiasm. Silver feels that Elderhostel faculty "have a special rapport with older people, they listen to us. There's giving and taking, and we teach them something too." "Seniors are much more motivated than younger students," says Moody, "and they bring that priceless dimension of life experience to classes."

"People were extremely young in their minds and curious," says Allan Rubin, a New York painter who worked in an arts Elderhostel at Stevens Institute. "There was no difference between them and a group of younger students except that they were interested in information and in getting in touch, not in getting ahead."

Bojanowski says, "I have faculty standing in line waiting to teach in Elderhostels. It's the most enthusiastic audience they can have and they get a lot of feedback. People want to know. We leave a half hour at the end of classes for all the questions."

Rice has had students who write to her four years after a course with clippings about the topic they thought might interest her. She knows one professor who considered resigning after 21 years of teaching because he felt he was making no impact on students, but remained after leading a course for older people, buoyed by the number of them who remembered and valued courses they'd taken 50 years ago.

Adds Moody, who has taught both undergraduates and seniors, "When you ask at the end of a class, 'Are there any questions?' younger students say, 'What do I need to know for the final exam?' But the older people will say, 'I don't think Plato was right about this because in my life it didn't happen that way.' And we talk about it."

And that's the beginning, not the end, of education.

Further information on the programs in this article can be obtained by contacting:

-- Elderhostel, 80 Boylston St., Suite 400, Boston, Mass. 02116; (617) 426-8056; maximum cost for U.S. programs, $195/week including room and board.

-- Senior Center Humanities Program, The National Council on the Aging, Inc., 600 Maryland Ave. SW, West Wing 100, Washington, D.C. 20024; (202) 479- 1200; programs free.

-- Institute for Learning in Retirement, American University, 4400 Massachusetts Avenue NW, Washington, D.C.; (202) 885-3920.

Information on educational opportunities for seniors, including financial aid, and minicourse outlines in over 30 subjects for self or group study are also available from:

-- Institute of Lifetime Learning, American Association of Retired Persons, 1909 K St. NW, Washington, D.C. 20049; (202) 662-4895.

Linda Barrett Osborne, a Washington writer, frequently covers the concerns of senior citizens.