KIDS WILL GET TO MAKE green slime for the last time Saturday and next Sunday at one final Community Days weekend at the Capital Children's Museum near Union Station. The chemistry lab demonstration is one of the museum's traditional favorites. The end is caused by good news: The 30-year-old museum is closing its doors Aug. 22 (two weeks earlier than previously announced) to prepare properly for a bolder future. It plans to reopen in June 2008 in a 140,000-square-foot, state-of-the-art interactive space in a revitalized L'Enfant Plaza. The building will be designed by the renowned architect Cesar Pelli. But say goodbye now to the red-brick former convent behind the train station, and to the Mayan pyramid, color world, brain teasers and Chuck Jones animation lab housed there. Existing exhibitions will not be re-created in the new venue. As for the Nek Chand Fantasy Garden sculptures that greet visitors at the museum's front doors, only a small grouping will be kept for the new building.
-- Linda Hales
At the Capital Children's Museum, 800 Third St. NE. Open daily 10 a.m. to 5 p.m. through Aug. 22. Free admission Saturday and next Sunday; $5-$7 otherwise. Call 202-675-4120 or visit www.ccm.org.
SAD BUT TRUE: For newcomers to his music, the shorthand tag for Big Boi is "the other guy in OutKast," which is to say the half that didn't write "Hey Ya," the standout track from last year's double album "Speakerboxxx/The Love Below." But as fans of "S/TLB" know, Big Boi (aka Antwon Patton) doesn't need to ride the shoulders of his eccentric and tour-wary partner, Andre 3000. The "Speakerboxxx" disc was essentially a Big Boi solo effort -- and one of the best rap albums of the year. Few hip-hop artists can blend message and music with quite the same ease, or in as many styles, and the problems that worry the guy are so real-world they're kind of funny. "My daughter doesn't want me at her PTA meetings," he rapped on a song called "The Rooster." That's a rap any daddy will understand.
-- David Segal
At Merriweather Post Pavilion in Columbia. Saturday at 5 p.m. $10. Call 202-397-SEAT or visit www.merriweathermusic.com.
THE SIXTH ANNUAL "Screen on the Green" film festival is underway, and the program this year is studded with classic favorites from years past. Tomorrow, pull up a blanket and a cooler on the Mall and watch "Dr. Jekyll and Mr. Hyde," Victor Fleming's 1941 adaptation of the Robert Louis Stevenson novel, in which Spencer Tracy stars as the tortured title character. (Debate among yourselves whether Tracy or Fredric March, who had played the role 10 years earlier, was a better Jekyll and Hyde.) Upcoming titles include "Whatever Happened to Baby Jane?," "The Thin Man" and "Mr. Smith Goes to Washington."
-- Ann Hornaday
On the Mall between Fourth and Seventh streets NW. Tomorrow at sunset. Free. Call 877-262-5866.
FRANCIS POULENC IS best known for his blithe, breezy evocations of high Parisian sophistication. As such, the composer's final opera, "Dialogues of the Carmelites," came as a shock when it was first performed in the late 1950s. Set during the French Revolution's climactic "Reign of Terror," this is the story of a convent of nuns who face political persecution with all the faith they can muster. Opera International has chosen a grim but effective work of music theater to mark its 10th anniversary on the Washington scene.
-- Tim Page
At Lisner Auditorium, 21st and H streets NW. Friday at 7:30 p.m. and next Sunday at 4 p.m. Staged in French with English supertitles. $20-$50. Call 301-365-3479 or visit www.operaintl.org.