Born the humble Pluto Platter (that's what it was called by the Wham-O Company back in 1957), the Frisbee has become part of our culture. Catch some of the action at the annual Frisbee festival 11:30 to 5 Sunday on the Mall between Third and Fourth SW. Besides workshops for slingers of every level, there'll be the Gaines Invitational World Championships, a canine disk-catching contest that's sure to bow-wow you over. And everyone can take part in the "Big Throw," an attempt to break the world record for the most Frisbees in the air at once. It's free. Call 870-2188.


The International Children's Festival gathers more than 35 performance groups -- including dancers, magicians, mimes and musicians -- for three days full of entertainment and hands-on workshops that include Mexican flower-making, Chinese kite-making and Polish paper-cutting. It's 11 to 4 Saturday, Sunday and Monday at Wolf Trap Farm Park in Vienna. Tickets are $6 for adults, $4 for kids 4 to 12, at the gates. Call 941-1527.


The Koi Festival at the Lilypons Water Gardens in Maryland pays honor to the Japanese carp that swim beneath the water lilies 11 to 5 Saturday and Sunday. Besides the exotic fish (which cost up to $5,000 apiece) there'll be live bluegrass and jazz, jousting and karate demonstrations and kite flying. Horticulture expert Steven Davis will answer questions. Admission is free, but it's $3 to park. At 6800 Lilypons Rd. in Lilypons, off Rte. 85 eight miles south of Frederick. 428-0686.


A Labor Day weekend sampler:

The National Symphony, conducted by Andrew Litton, performs on the West Lawn of the Capitol at 8 Sunday in a program including works by Gershwin and Tchaikovsky. (Rain date is at 8 Monday.) 254-3600.

Kensington's Labor Day Parade and Festival runs 10 to 5 Monday on Howard Avenue and Antique Row with street shopping, music, food, exhibits and a parade at 10. 949-2424.

Gaithersburg's 49th annual Labor Day Parade with grand marshal Walt Starling is at 1 Monday at East Diamond and Russell avenues. Call 948-0660.

The Greenbelt Labor Day Festival is 6 to midnight Friday, 9 to midnight Saturday and Sunday and 9 to 6 Monday with a carnival, game and food booths, a tennis tournament and a parade at 10 Monday. 982-0368.


The fourth annual ADD Arts Festival fills downtown D.C. with a hefty mix of poets, painters, actors, dancers and musicians. Between 6 and 11 Saturday groups including the Shirley Horn Trio, Gary Thomas Quintet and Smith Sisters perform on Western Plaza (14th and Pennsylvania NW). Sunday noon to 8 at Gallery Place (Eighth and F NW), West African group ODADDA!, Ajax Moving Co. dancers, HWB Theater Company and tap dancer Johne Forges (of Cafe' Lautrec fame) keep things moving. Take a cue from D.C. artists Michael Clark and Kevin MacDonald (among others) and add your masterpiece to the Artists' Invitational Graffiti Wall (Ninth and F NW). All day Sunday, d.c. space (Seventh and E NW) has poetry readings and cabaret theater, all free. Call 783-0360 or pick up a complete schedule at most Metro stations.


Oatlands Plantation Draft Horse and Mule Day is 10 to 5 Saturday in Leesburg. More than 75 Belgians, Clydesdales, Suffolks and other work horses will show you how surefooted they can be in such events as obstacle racing, plowing, seeding and fence jumping. Oatlands is on U.S. 15, five miles south of Leesburg. Admission is $5, under 12 free. 703/777-3174.


Ocean City's Saltwater Festival has a beach full of free family entertainment noon to 8 Saturday and Sunday, including the Bits 'n' Pieces Puppet Theater, scarecrow-maker Mark Baron and vaudevillian Laura Dirksen Green plus a dozen other entertainers at the Convention Center. Fireworks over the Bay will close the festival. Call 800/49-BEACH in Maryland or 800/62-OCEAN.

On the way out, Crisfield's 40th National Hard Crab Derby faces off some of the fastest and meanest critters you'd ever want to eat, alongside boat-docking races, live bluegrass and the National Crab-picking Championship at 3 Saturday. It's 10 to 9 Friday, 8 to 11 Saturday and 8 to 9 Sunday. Crisfield is on Rte. 413, off U.S. 13, about 35 miles south of Salisbury. 301/968-2682.


Check out the Viva Brasil Festival noon to 5 Saturday at the Old Post Office Pavilion at 12th and Pennsylvania NW. To celebrate Brazilian Independence Day, five bands, including the fusion group Tropic of Capricorn, will perform and samba dancers will show you how it's done. Free. 289-4224.


The Town and Country antique show at Mount Vernon College at 2100 Foxhall Rd. NW is 11 to 9 Friday and Saturday, 11 to 7 Sunday and 11 to 5 Monday. $5 for all four days. 333-9880 . . . The Washington Bridge League Labor Day Tournament is open to all players beginning at 1 Friday through Sunday at the Omni-Shoreham, 2500 Calvert St. NW. $6 to $8 per session. 234-0700 . . . Austrian classical guitarist Helmut Jasbar performs free at St. John's Episcopal Church (34th and Rainier Avenue) in Mt. Rainier at 4 Sunday. 927-1156 . . . the Warrenton Horse Show at the show grounds on U.S. 29 in town (don't take the bypass) is 8 to 6 Friday, 8 to 6 and 8 p.m. to 11 p.m. Saturday, 7 p.m. to 11 Sunday and 8 to 6 Monday. $3, $1 for kids under 12 per show. 703/347-9442 . . . the U.S. Navy Commodores Jazz Ensemble performs on the West Terrace of the Smithsonian's Air and Space Museum at noon Friday. Free. 433-2525 . . . Celtic Thunder, Uptown and Lenny Cuje' Quintet gather for a free concert at 1:30 Sunday at Foundry Mall (30th and Thomas Jefferson NW in Georgetown) 862-1300.