If you look sharp, you can listen, mister (and sister), to the smooth melodies of barbershop quartets this weekend:
X The Arlingtones Barbershop Chorus hosts three shows of Big Top Barbershop: A Circus of Harmony, a program of circus songs and comedy at Arlington's Thomas Jefferson Center, 125 South Old Glebe Road. The bill also includes the internationally acclaimed quartet Vaudeville. Shows are Friday at 8:15; Saturday at 2:15 and 8:15. Tickets are $7; $4 for students and seniors. 527-6195.
X And the Old Post Office Pavilion, 1100 Pennsylvania Avenue NW, gets in tune this Sunday from 1 to 2 with Penn Villains, a comedy barbershop quartet from Pennsylvania. Free. 289-4224. Whiz Kids
Forty high-schoolers from around the country zero in on the future when they exhibit their prize-winning projects in Westinghouse's Science Talent Search this Saturday and Sunday from 1 to 4 at the Great Hall of the National Academy of Sciences. And we're not talking about two tin cans connected by a string, but projects such as an underwater energy conservation device that generates electricity from ocean waves. If you don't quite understand a thing or two, the kids will be happy to explain. So will two Nobel laureates, on Sunday. The academy is on C Street between 21st and 22nd streets NW. For more information, call 347-3000, extension 660. Beauty Binge
If you've been losing your beauty sleep lately, you may want to hit New Faces of '86 -- A Beauty Fashion Festival, two days of live music, fashion shows, cosmetic demonstrations and makeovers at the Washington Convention Center. There'll be guest appearances each day by the 1986 Chippendale Calendar Models, Mary Lou Retton and Miss Universe Deborah Carthy- Due. The show is Sturday and Sunday from noon to 8. Tickets are $3; children under 12 are free. 639-4884. Wars of Yesteryear
History buffs can do some delving this weekend:
* The paintings of six leading British and American aviation artists will be displayed as part of a World War II Symposium this Saturday from 6 to 10:30. Some of the prints are signed by flying aces of the period. And speaking of hot pilots: No. 3-ranked Luftwaffe ace General Guenther Rall will speak about his experiences on the Russian Front from 1941 to 1945; and Colonel Don Lopez, an Air Force ace in China and now with the Air and Space Museum, will moderate questions from the audience after the talk. The event is at Twin Bridges Marriott Hotel, 333 Jefferson Davis Highway, Arlington. Tickets are $12 at the door; 548-4440.
* Toy soldiers take to the battlefield as 700 wargamers converge on the Fourth Annual Historical Miniatures Mini- Convention and theorize about how history might have changed if only . . . Novices can just watch or try their own strategies. It's at the Ramada Inn, Princess Garden Parkway, Lanham. Admission is $6. Hours are Friday, noon to 7; Saturday 9 to 7; Sunday 9 to 6. 459-1000. Bluegrass Bonanza
Takoma Park kicks off a series of free contemporary bluegrass concerts by the U.S. Navy's Country Currents, a five-piece band that has played the White House lawn with Charlie Daniels and Juice Newton. Banjo master Bill Emerson directs the one- hour concerts, every Sunday at 3 through March 23, in the Takoma Park Municipal Building, 7500 Maple Avenue off Route 410. 433-2525 or 270-4048. Orchestral Jazz
The D.C. Community Orchestra sponsors Music of Black Composers and Artists, a free concert saluting Black History Month. The 40-piece orchestra plays selections from "Porgie and Bess," the spirituals of Nathaniel Dett and the "Danse Negre" of Samuel Coleridge-Taylor. The Ambassadors Jazz Ensemble kicks in with classic Duke Ellington numbers such as "Take the A Train." The concert is Sunday at 4 at Ballou Senior High School, Fourth and Trenton streets SE. 362-4398 or 364-0575. Rest of the Best
The United States Air Force Band continues its free Guest Artist Series Sunday with Metropolitan Opera tenor John Alexander. The concerts are at DAR Constitution Hall, 18th and D streets NW. 767-5658 . . . Poet John Ciardi will read from his translation of Dante's "Divine Comedy" this Sunday at 7:30 in the Hirshhorn Museum Auditorium, Seventh Street and Independence Avenue NW. $8; students $5. 357-3030 . . . Home Expo '86 is at the Starplex/Armory, 2001 East Capitol Street. Hours are Friday and Saturday, noon to 10; Sunday noon to 8. Tickets are $3.75. By Metrorail, exit at the Stadium/ Armory station from the Orange/Blue lines. 547-9077 or 547-9215 . . . There'll be a Big Night Out Swing Dance and Workshop Saturday at 8 in Lloyd Gymnasium, Mount Vernon College, 2100 Foxhall Road NW. Admission is $6. Call 229- 4188 or 270-6270
Five-hundred exhibitors show their work at the 10th Annual ACC Craftfair at the Baltimore Convention Center, 1 West Pratt Street. Admission is $5; children under 12 are free. Show hours are Friday 11 to 8; Saturday 11 to 6; Sunday 11 to 5. 301/962- 1122 . . . Fifteen dealers will be on hand at Montgomery College's Second Annual Baseball Card Show Saturday from 10 to 5. The show is on the second floor of the Fine Arts Building, Route 355 and Mannakee Street, Rockville. Admission is $1. 256-3899 or 279-5218.
Actor Stephen Henderson performs a one- man show this Sunday at 2 in the Harris Theater at George Mason University, 4400 University Drive, Fairfax. Henderson will read excerpts about Sally Heming, Thomas Jefferson's slave/concubine, from Faun Brody's biography "An Intimate History of Thomas Jefferson," and selected readings from South African playwright Athol Fugard. Tckets are $9; $7 for students and seniors. 362-2940 . . . The Prince William Symphony Orchestra plays music by Weber, Saint-Saens, Elgar and Tchaikovsky Saturday at 8 at Potomac High School, 16706 Jefferson Davis Highway, Woodbridge. There'll be a repeat performance Sunday at 3 at Osbourn Park High School, 8909 Euclid Avenue, Manassas. Tickets are $6; $4 for students and seniors. 703/361-4614 . . . Woodlawn Plantation kicks off its 23rd Annual Needlework Exhibition this Friday from 9:30 to 4:30; the show runs daily through March 23, with continuous demonstrations. Admission is $4 for adults; $2 for children. The plantation is at the intersection of Routes 1 and 235. 557- 7881.