CRAZY CONSTRUCTION -- Today, 1-4 p.m. After examining Frank Gehry's steel and glass buildings and other extraordinary creations, construct your own structures using shiny "building" materials. National Building Museum, 401 F St. NW. $4 per project. 202-272-2448.
LABOR DAY PARADE -- Monday at 1 p.m. The 67th annual parade commemorates the unofficial end of summer and includes fire engines, high school marching bands, costumed characters, dance groups, clowns, horses, floats and giant balloons. East Diamond and Russell avenues, Gaithersburg. Free. 301-258-6350. For a route map, see www.gaithersburgmd.gov.
YOUNG PLANETARIUM -- Wednesday at 4 p.m. Ages 2-10. An introduction to the night sky for budding astronomers. Nature Center, 5200 Glover Rd., NW. Free. 202-895-6070.
CURIOUS CORN -- Thursday at 9:30 a.m. and 11 a.m. Saturday at 10 a.m. Stories and crafts teach fun facts about the crop. Hunt for corn in the gardens, then sample a corny treat. Green Spring Gardens Park, 4603 Green Spring Rd., Alexandria. $5. For reservations, call 703-642-5173.
ARTS SAFARI -- Saturday, 10 a.m.-6 p.m. Ages 6 and older. The 10th annual workshop includes hands-on activities such as paper mache, clay sculpture, safari murals, tie-dye projects, plaster body casting and a scavenger hunt. Torpedo Factory Art Center, 105 N. Union St., Alexandria. Free. 703-838-4565.
QUILTING DEMONSTRATION -- Saturday, 11 a.m.-noon and 1 p.m.-2 p.m. Ages 6-12. A hands-on quilt-making display. Gaithersburg Community Museum, 9 S. Summit Ave., Gaithersburg. $2. For reservations, call 301-258-6160.
WINGS OF FANCY -- Through Sept. 18. Live butterflies from Central and South America and Maryland are featured in an indoor exhibit and in the outdoor gardens. Brookside Gardens, 1800 Glenallan Ave., Wheaton. $4.50, ages 3-12 $3.50, 2 and younger free. 301-962-1400.