This weekend the Old Post Office Pavilion features a free "Taste of Scotland" festival, with Scottish country dancers on Saturday at 2 and 3, and Highland dancing to bagpipe music at 4 and 5. On Sunday, the New Findhorn Ceilidh Band will play a variety of traditional Scottish and English tunes from 1 to 3. On both days you can take a double- decker bus from the Pavilion to the National Gallery of Art to the Treasure Houses of Britain exhibit. The free shuttle runs from noon to 4. Tickets for the exhibit must be picked up at the gallery. The Pavilion's at 1100 Pennsylvania Avenue NW; if you're taking Metrorail, exit from the Orange and Blue lines at Federal Triangle. 289-4224. A Jump on Seoul
The 1988 Olympics in Seoul aren't that far off. And you can catch a little pre- Olympic action this weekend when some of the nation's top female gymnasts compete in the Ninth Annual Capital Cup Gymnastics Tournament at Montgomery College Gymnasium (off Rockville Pike) in Rockville. Gymnasts from more than 50 teams will be bending over backward in a variety of events, including the balance beam and uneven bars. There'll be four preliminary sessions -- three on Saturday, at 9, 1:30 and 6; one on Sunday at 9. The finals are Sunday at 2. Tickets are $4, $3 for children under 13 on Saturday; $5 on Sunday. 424-8545. A Different Duke
Native Washingtonian and legendary jazzman Duke Ellington considered his trilogy of sacred concerts some of his most important work. You can hear selections from them this Sunday at 8 in a free concert at the New York Avenue Presbyterian Church. Among the performers will be the D.C. Jazz Workshop Orchestra, the D.C. Contemporary Dance Theater, tap dancer Johne Forges and two vocal soloists. The church is at 13th Street and New York Avenue NW. Tickets are available at the Ticketplace, D.C. Space, Melody Records and at the door. 783-0360. Tuba To-Do
Eleven pipers piping, no big deal. Seventy- six trombones sliding, maybe. But a hundred tubas oomphing? In case you haven't heard the news, tuba players great and small will take part in "TubaChristmas" this Sunday at 7 on the Ellipse (behind the White House). Davey Marlin Jones will conduct the free half-hour concert. 944-8331. Sneak Preview
It's going to look a lot like Times Square this New Year's Eve at the Old Post Office Pavilion and The Shops at National Place. While there'll be plenty of action outdoors -- including an appearance by James Brown -- you could be one of the lucky few admitted to celebrate indoors as well, where the festivities will include food, drink and plenty of jazz at both locations. To get your free ticket, line up at 9:30 a.m. this Tuesday at Ticketplace on F Street between 12th and 13th streets NW. Limit is two tickets per person. The first thousand tickets are for admission to the Pavilion; the next 1,500 are for National Place. 727-6600. Away in a Manger
Would you walk a mile for a camel at Christmas? If so, bundle up and head on over to the Takoma Park Seventh-Day Adventist Church this Friday through Christmas Eve for free outdoor performances of its National Nativity Drama, complete with live camels, horses, sheep and even an 80-member cast. The church is at 6951 Carroll Avenue. In addition, as part of Takoma Park's holiday celebration, there'll be mini-concerts with the Y.E.S. Choral Group on Saturday and the Norman Barnacle Choir on Sunday, from 7 to 7:30 at the gazebo near the church. If you're taking Metrorail, exit from the Red line at the Takoma Metro station. 270-1700. Making Tracks
Trains and Christmas go together, and never better than at the "Old Fashioned Christmas Gardens" exhibit at Ellicott City's B&O Railroad Museum. From noon to 8 this Saturday and Sunday, five special train displays, both modern and antique, will be set up among Christmas trees and other decorations adorning the museum. While you're there, you can also take in a slide show of the history of the B&O Railroad. The museum is at Main Street and Maryland Avenue, Ellicott City, Md. Take I-95 north toward Baltimore to Route 32 west; go north on Route 29 to east on Route 40. Follow signs to Ellicott City Historic District. Adults $1.25; 75 cents for children under 13. 301/461-1944. Rest of the Best
Rock Creek Park Nature Center offers a 45- minute program, "A Civil War Christmas," depicting the camp life and diversions of the soldier, Saturday at 11. 5200 Glover Road NW; 426-6829; free.
There'll be traditional Bavarian holiday music and dancing, strolling minstrels, mimes and magicians at Baltimore's German Festival at Lexington Market, 400 West Lexington Street, from noon to 3 Saturday; 301685-6169; free admission . . . Also in Baltimore, The Babe Ruth Museum opens a new exhibit, "Five Greatest Moments in Orioles History," which includes the Orioles' 1966 World Series Championship and Earl Weaver's last game. It's open Saturday and Sunday from 10 to 4. The museum is at 216 Emory Street. Adults $2.50; $1.25 for children under 13. 301/727-1539
Jonathan Edwards performs Friday at 8 at The Barns at Wolf Trap. $12. Also at The Barns on Saturday, New Grass Revival performs at 8. $10. 1624 Trap Road in Vienna. 703/938-2404.