KIDDY HOP -- Today, 1-4 p.m. A family swing dance with lessons. Glen Echo Park, Bumper Car Pavilion, 7300 MacArthur Blvd., Glen Echo. $10 per family. 301-320-7757.

AIR AND SPACE FAMILY DAY -- Saturday, 10 a.m.-5:30 p.m. Learn how airplanes fly with hands-on activities. National Air and Space Museum, Steven F. Udvar-Hazy Center, 14390 Air and Space

Museum Pkwy., Chantilly. Free. 202-357-2700.

FESTIVAL OF THE BUILDING ARTS -- Saturday, 10 a.m.-4:30 p.m. Build a brick wall; try stone carving, woodworking and nail-driving; make a sculpture out of nuts and bolts; and climb aboard bulldozers at a construction equipment "petting zoo." National Building Museum, 401 F St. NW. $5 suggested donation. 202-272-2448.

INTERNATIONAL CHILDREN'S FESTIVAL -- Saturday and Sept. 19, 10 a.m.-4 p.m. See performers from China, India, Peru, Saudi Arabia and South Korea. Hosted by Bob McGrath of "Sesame Street" and Matt Gallant of "The Planet's Funniest Animals." Includes craft and technology workshops and an animal show. Wolf Trap, Filene Center, 1551 Trap Rd., Vienna. $10, ages 3-12 $8. 703-218-6500 or 703-255-1860.

ARTS ON FOOT FESTIVAL -- Saturday, 11 a.m.-5 p.m. Make an artist's book with stories and pictures. Sponsored by the National Museum of Women in the Arts. F Street between Seventh and Ninth streets NW. Free. 202-783-7370.

GROW WITH PLANTS -- Saturday, 11 a.m.-4 p.m. Lynne Cherry, founder of the Center for Children's Environmental Literature, reads from "How Groundhog's Garden Grew." With workshops on gardening and composting. Brookside Gardens, 1800 Glenallan Ave., Wheaton. Free. For reservations, call 301-962-1451.