Learning Vacations : Class-Act Vacations : Lessons: From nature study to esoteric sports, these programs focus on learning.

Where do you go after Disney World? Maybe back to school, if you want a family vacation that combines learning with fun.

Generally, programs that welcome families are scheduled in the summer to take advantage of school breaks, and almost always involve a lot of outdoor activities. The focus of many is nature, but some provide an opportunity to learn a new skill--very often an outdoor sport, such as sea kayaking. These vacations can be fairly rugged or comfortably relaxed. A few are open to children of all ages; others are limited to older teens.

Finding these programs is not easy; most are small operations with limited funds for advertising. However, ads do appear occasionally in such travel-oriented magazines as Travel & Leisure, Southern Living and Outside. At several U.S. national parks, including Wyoming’s Yellowstone and Colorado’s Rocky Mountain, educational institutes put together learning programs for families. Also, check with the tourism office of the state in which you are interested in vacationing.

Among the North American possibilities:

-- Wildlife lessons in Montana. Wildlife conservation is the theme of the family “edu-vacation” program at Lake Upsata Guest Ranch, which sits beside a small, woodland lake in the Blackfoot Valley of western Montana near Ovando. Wildlife biologists conduct informal wildlife seminars about wolves, waterfowl, elk, owls and other wilderness creatures, many of which can be spotted on the ranch.

When lessons are over, guests can sign up for fly-fishing courses or go canoeing, mountain biking, boating, hiking, rafting or take an escorted trail ride in the neighboring Bob Marshall Wilderness. The program is available from now into the fall.

Lodging is in six comfortable cabins with private baths or in a Native American tepee with nearby showers and toilets. The cabin rate, which includes all meals, is $155 a day for adults and $125 for children under 12. Tepees cost $75 a day per person for any age. There is a three-day minimum stay. Information: P.O. Box 6, Ovando, Mont. 59854; telephone (800) 594-7687.

-- Adventuring in Yellowstone. Families can explore the thermal fireworks of Yellowstone National Park with a guide or join a horse-packing expedition into a wilderness area. Both outings and others designed for the family are organized by the Yellowstone Institute, an educational offshoot of the park.

“Family Days in the Thermal Basins” is a three-day class, July 22 to 24, which serves as an introduction to the park’s geysers, emerald pools and other geological attractions. The price is $75 per person, and the classes gather daily at the Madison Campground. Participants can camp there, reserve a room in one of Yellowstone’s lodges or stay in a motel in nearby West Yellowstone, Mont.

On the four-day family horse-packing trips, beginning Aug. 10 and 17, participants learn how to camp and travel in the wilderness without damaging the fragile countryside. These are fairly rugged trips, and everyone is expected to pitch in with the cooking and clean-up chores. The price is $420 a day, including all meals. Information: Contact the Institute at P.O. Box 117, Yellowstone National Park, Wyo. 82190; tel. (307) 344-2294.

-- Folk dancing, fiddling and crafts in West Virginia. For five weeks each summer, the Augusta Heritage Center puts together a menu of folk art classes that range from Cajun and Irish dancing to storytelling and rug-weaving. The six-day sessions are held on the campus of Davis & Elkins College in Elkins, W.Va.

Students age 17 and under may sign up for many of the adult courses, and other courses have been organized for younger children. The fee for the classes is $255 or $265 per person. The weekly sessions begin July 10, 17, 24 and 31 and Aug. 7. Lodging is in campus residence halls in two-person rooms, and the six-night room rental of $190 per adult includes all meals in the cafeteria. The rate is $75 for a child age 8 to 13 who shares the room in a sleeping bag, $115 for a child age 14 to 17. Information: Registrar, Augusta Heritage Center, Davis & Elkins College, 100 Campus Drive, Elkins, W.Va. 26241; tel. (304) 636-1903.

-- Kayaking in British Columbia. Ecomarine Ocean Kayak Centre of Vancouver offers kayaking excursions on British Columbia’s ruggedly beautiful western coast. Adventures are geared to adults, but older teen-agers with one or both parents are welcome.Most nights are spent camping. The three-day trip in the central Gulf Islands of Georgia Strait is about $295 per person; the six-day trip in Clayoquot Sound is about $630 and the eight-day trip in the Broughton Archipelago off the northeast coast of Vancouver Island is about $825. Trips run throughout the summer. Information: Ecomarine Ocean Kayak Centre, 1668 Duranleau St., Vancouver B.C. V6H3S4; tel. (604) 689-7575.

-- Nature studies in the Rockies. Teen-agers with strong academic interests may join their parents in a wide variety of scholarly seminars in Rocky Mountain National Park. Typically, indoor lessons are followed by field trips, and most seminars require hiking at high altitudes.

Most classes meet at Hidden Valley Lodge, 10 miles west of Estes Park, Colo. Participants can camp free near the lodge or stay in Estes Park. Information: Rocky Mountain Nature Assn., Rocky Mountain National Park, Estes Park, Colo. 80517; (303) 586-1265.