POND PLANTS, aquaculture specialist Howard Crum discusses plants appropriate for a backyard pond, 10 a.m., National Arboretum, 3501 New York Ave. NE. $10. 202-245-5898.
BLACK FAMILY REUNION, cultural exhibits, health screenings, international arts and crafts, food and live music, 10 a.m.-8 p.m. Saturday, noon-8 p.m. Sunday, Washington Monument grounds, Independence Avenue and 15th Street NW. Free. 202-737-0120.
LANDSCAPE GARDENING TALK, Martin Mosko and Alxe Noden discuss the use of cascading water, gently swaying trees and mounds of boulders, 10:30 a.m., U.S. Botanic Garden, 245 First St. SW. $12; reservations required. 202-226-4082.
CHILDREN'S BOOK, NATURE EVENT, author Mary Quattlebaum reads from her books "Family Reunion" and "Jackson Jones and Mission Greentop"; activities include painting garden pots, creating seed art, drawing and painting flowers and plants, with artist Peter Waddell, light refreshments, 11 a.m.-3 p.m., Tudor Place, 1644 31st St. NW. $15; children, free; reservations required. 202-965-0400, Ext. 109.
HISTORY REENACTMENTS, actors portray lawyer Charles Hamilton Houston, Supreme Court Justice Thurgood Marshall, a Jewish peddler, an enslaved African American and an African American Civil War soldier as they tell tales of their pursuit of freedom, noon, 2 and 4 p.m. Saturdays and Sundays, through Sept. 19, National Museum of American History, 14th Street and Constitution Avenue NW. Free. 202-633-1000.
ROCK CREEK PARK HIKE, for ages 7 and older, a park ranger leads a half-mile exploratory walk along Woodland Trail, 2 p.m., Rock Creek Park Nature Center, 5200 Glover Rd. NW. Free. 202-895-6070.
GARDEN DESIGN TALK, Fran Sorin discusses how she turns outdoor spaces into beautiful gardens, 2-3:30 p.m., U.S. Botanic Garden, 245 First St. SW. $5; reservations required. 202-226-4082.
WORLD WAR II PHOTO EXHIBIT, curator Michelle Delaney discusses the museum's efforts to collect photographs and family albums from the 1940s and photographs by Robert Capa, the Scurlock Studio and Navy photographer John Wesley Stipe, 2 p.m., National Museum of American History, 14th Street and Constitution Avenue NW. Free. 202-633-1000.
ARBORETUM BIRD-WATCHING, led by an arboretum staff member, 5-6:30 p.m., National Arboretum, 3501 New York Ave. NE. $8; reservations required. 202-245-5898.
"CANSTRUCTION BUILD-OUT," teams of architects, engineers and contractors create models of office buildings, hotels, theaters and more using canned goods during a six-hour period, visitors vote for their favorite structure and are encouraged to bring a canned good for the Capital Area Food Bank, 6 p.m.-midnight, the Mall at 2000 Penn, 2000 Pennsylvania Ave. NW. Free; reservations required. 202-667-1798.
PERSECUTION VICTIMS REQUIEM, Michael McCarthy conducts the combined cathedral choirs and soloists Diane Atherton, Barbara Hollinshead and Steven Combs in a performance of Stale Kleiberg's "Requiem for the Victims of Nazi Persecution"; the composer discusses his work, 7:15 p.m., Washington National Cathedral, Massachusetts and Wisconsin avenues NW. $10, $25. 202-537-5757.
KENNEDY CENTER OPEN HOUSE, celebration of its 33rd birthday with dance and music performances and activities showcasing native cultures of the Americas and Puerto Rico, 11:45 a.m.-7 p.m., 2700 F St. NW. Free; some events require free tickets. 202-467-4600.
ADAMS MORGAN FESTIVAL, art market, live music, crafts, ethnic-food booths, youth activities, vendors, arts and crafts, and more, noon-6 p.m., 18th Street NW between Florida Avenue and Columbia Road. Free. 202-232-1978 or www.ammainstreet.org.
KALORAMA HOUSE,EMBASSY TOURS, self-guided visits to the Woodrow Wilson House, residences of the ambassadors of Chile, Romania, Hungary and Bolivia, and other residences, sponsored by Friends of the Wilson House, noon-5 p.m., tickets include a program on the architecture and history of each site, tour begins at the Wilson House, 2340 S St. NW. $25; in advance, $22. 202-387-4062, Ext. 18.