Three major Washington institutions kick off their autumn seasons this weekend. On Friday, the Kennedy Center opens its tenth year of programming for young audiences with "A Family Album," the first of four contemporary American plays (27 free performances) through December. Based on conversations with children about their family lives, the musical play centers around five households.

The Smithsonian Resident Associate program begins its Discovery Theater season with performances Friday and Saturday of Hans Christian Andersen's "The Ugly Duckling," performed with hand puppets.

Also on Saturday morning, families can take a special tour of the National Gallery's East Building following a 20-minute film made especially for introducing children to the world of art. This program runs every Saturday trough December.

All events are free unless otherwise noted.

NATIONAL ZOO -- Open daily; gates open from 8 to 8; animal buildings, 9 to 6; panda feedings, 11 and 3; elephant training demonstrations, 2; Sea lion training demonstrations, 2, 3001 Connecticut Ave. NW, on the Metro Red Line. Family learning centers Zoolab and Birdlab open Friday through Sunday, noon to 3; Herplab open Wednesday through Sunday, noon to 3. 673- 4717.

OXON HILL FARM -- Open daily, 8:30 to 5, Oxon Hill Road (take Beltway exit 3A, turn right on Oxon Hill Road). Saturday, 1, "Autumn on the Farm." Join a farmer for a stroll around the farm; meet at the barn. Sunday, 11 to 1, "Lead Ropes." Watch a farmer demonstrate how to move horses safely. 839-1177.

NATIONAL AQUARIUM -- Open daily, 9 to 5, Department of Commerce, 14th and Constitution Avenue NW. The sharks are fed Monday, Wednesday and Saturday at 2; weekday features are a touch-tank, mini- theater and a thousand types of marine life. School groups should schedule in advance. Adults $1; children 50 cents. 377-2825.

CEDAR HILL -- Open daily, 9 to 4, 1411 W St. SE, Anacostia. Cedar Hill, Frederick Douglass' home, recalls his work with films, interpretive exhibits and a house tour. 426- 5961 or 426-5962 or 426-5963.

USS BARRY -- Open daily, 10 to 5, Washington Navy Yard, Ninth and M streets SE. The Navy destroyer's weather deck is open for public viewing and self-guided tours. 433-3377.

CHILDREN'S MUSEUM -- Monday through Saturday, 10 to 4, Sunday 1 to 4, Rose Hill Children's Museum north of Frederick. Take U.S. 15 north to Exit 8 to Motter Avenue; follow Motter to left onto 14th Street and left onto North Market Street, follow signs to Rose Hill. Costumed tour guides conduct tours of the 1790 mansion. Hands-on exhibits include a loom, antique toys and spinning wheel. Adults $1; under 17, free. 301/694- 1646.

CAPITAL CHILDREN'S MUSEUM -- Daily, 10 to 5, 800 Third St. NE. Saturday and Sunday museum hours, make a slide by placing materials and textures between two pieces of plastic. $2. 543-8600.

DOLL'S HOUSE AND TOY MUSEUM -- Tuesday through Saturday, 10 to 5; Sunday, noon to 5, 5236 44th St. NW. Antique dollhouses, dolls, toys, games and an exhibit of antique cat games and toys. Adults $2; under 14, $1; group rates available. 244-0024.

NATIONAL COLONIAL FARM -- Tuesday through Sunday, 10 to 5, 3400 Bryan Point Rd., Accokeek. Sunday, 1 to 4, watch farm staff prepare a variety of colonial pumpkin dishes. Adults $1; children under 12, free. 301/283-2113.

DISCOVERY THEATER -- Tuesday through Friday, 10 and 11:30 a.m.; Saturday, 1 and 3; Discovery Theater, Arts and Industries Building, 900 Jefferson Dr. SW. Classic Stories, Enduring Tales: "The Ugly Duckling." A puppet production of the Hans Christian Andersen tale; recommended for pre-kindergarteneners through third grade. Adults $3; 12 and under, $2.50; group rates available. For more information and reservations, call 357-1500.

CLOISTERS CHILDREN'S MUSEUM -- Wednesday through Friday, 10 to 4:30; Saturday, 12 to 4, 10440 Falls Rd., Brooklandville, Maryland, "Indian Summer Celebration." Hunt bear and porcupine hidden along a nature trail, dance around a totem pole, and see an extensive Kachina doll exhibit. Saturday, museum hours, "Indian Crafts": decorate Indian headbands. $2 donation requested from adults; group tours available. 301/823-2551.

RAILROAD STATION MUSEUM -- Wednesday through Saturday, 11 to 4; Sunday, noon to 5, Main Street and Maryland Avenue, Ellicott City. The renovated station has a diorama of the trip of Tom Thumb (an early 19th-century train) from Baltimore to Ellicott City. There are also sight and sound shows, model train exhibits and tours of the museum. Adults $1.25; under 13, 75 cents.

COLONIAL FARM -- Wednesday through Sunday, 10 to 4:30, Claude Moore Colonial Farm at Turkey Run, 6310 Old Georgetown Pike, McLean. Take a self-guided tour of farm life for a low-income family in Colonial Virginia. Ongoing demonstrations of agricultural and domestic chores, such as spinning and candlemaking, round out this history lesson. Adults $1; children under 12, 50 cents. 703/442-7557.

TRAVELING FOOTBALL HALL OF FAME -- Friday-Saturday, 10 to 9:30; Sunday, noon to 5, 7101 Democracy Blvd., Montgomery Mall, Bethesda. The Pro Football Hall of Fame pays a visit; see the jersey of Johhny Unitas, Super Bowl rings, shoes and other select football memorabilia, videotapes, quizzes, photographs, Dan Marino football passing contest. 469-6000.

HARVEST FESTIVAL -- Friday and Saturday, noon to 5, Shiloh Baptist Church, 1500 Ninth St. NW. "Shiloh Harvest Festival," Scrabble, chess, amusement rides, karate demonstrations, hopscotch contest, knot tying and more. 232-4200.

CHILDREN'S STORY HOUR -- Friday, 4:30 to 5:30, Potomac Overlook Park Nature Center, 2845 Marcey Rd., off Military Road, Arlington. Naturalists tell stories for pre- schoolers and kindergarteners. 528-5406.

KENNEDY CENTER -- Friday, 7:30 p.m.; Saturday, 10:30 and 12:30; Sunday, 2, Theater Lab, John F. Kennedy Center for the Performing Arts, "Family Album." Vignettes of five families; live music, based on conversations with children. Free, but tickets are required. Call 254-3600.

CHILDREN'S RADIO THEATER -- Saturday, 8 a.m., WPFW 89.3 FM. "Why Black?" and "The Witch's Tale," two unusual stories about mayhem and witches. Listeners can participate in a call-in following each program by calling 783-3104.

SATURDAY MORNING AT THE NATIONAL -- Saturday, 9:30 and 11, Helen Hayes Gallery, National Theater. Alice McGill, poet and folklorist, tells African and American stories, sings songs and plays games. Reservations recommended. Call 783-3372, 24 hours a day.

DISCOVER THE GALLERY -- Saturday, 10 to 11:30, National Gallery of Art, Fourth and Constitution Avenue NW, "Discover the East Building." A program for families with children ages six to 12; see a film for kids, "Elements of Design," and take a tour of the museum. Free, but advance registration required. 842-6249

DRAFT HORSES AND MULES -- Saturday, 10 to 6, Belle Grove Plantation, U.S. 11, one mile south of Middletown, Va. (at intersection of I-66 and I-81), "Draft Horse and Mule Day." Log pulls, blacksmithing, coon mule jumping, wagon and buggy rides, sack races and mule rides. Adults $3; children, $1; under 6, free. 703/869-2028.

TROLLEY MUSEUM -- Saturday and Sunday, noon to 5, Northwest Branch Regional Park, Bonifant Road between Layhill Road and New Hampshire Avenue, north of Wheaton. Trolley rides: $1 adults; under 18, 75 cents; under two, free. 384-9797.

OLD POST OFFICE -- Saturday, noon to 6; Sunday, 1 to 5, Pavilion, 1100 Pennsylvania Ave. NW. The Post Office celebrates its second birthday. Saturday: mimes, balloon sculptor, scarecrow-making workshop and folk music. Sunday: children's dance groups on stage. 289-4224.

CHILDREN'S PLANETARIUM -- Saturday and Sunday, 1 and 4, Rock Creek Nature Center, 5200 Glover Rd. NW. First show for children four to seven (must be accompanied by an adult); second show for ages seven and up. No latecomers are admitted. 426-6829.

ADVENTURE THEATER -- Saturday and Sunday, 1:30 and 3:30, Adventure Theater, Glen Echo Park, Glen Echo. "The Magic Flute," a one-hour marionette version of Mozart's opera in English, featuring dragons, flying horses and enchanters. $4, group rates available. 320-5331 weekdays and performance days from 10 to 2.

BLUE SKY PUPPETS -- Sunday, 2, Rock Creek Nature Center, 5200 Glover Rd. NW, "Lights Out on the Bunny Brothers." A 45- minute presentation featuring singalong, music, puppet show and other entertainment relying on audience participation. 426-6829.