This year more than 100 films will be shown, among them Ken Burn's "The National Parks: America's Best Idea," a look at our wild backyard in "Appalachia: A History of Mountains and People" and an examination of a growing crisis with "Blue Gold: World Water Wars." See the festival Web site for a full list of films.

Festival schedule for March 20-22

"CHARCOAL TRAFFIC & SOLAR COOKING IN BENDER BAYLA," "MANDA'S PRIZE," "SOLAR COOKING IN MADAGASCAR, A MEANS TO HALT DEFORESTATION" AND "THIRSTY PLANET" Forests are being cut down to be used for cooking. Can solar cookers remedy that need? A discussion follows. Noon at the Sumner School Museum, 1201 17th St. NW. 202-442-6060. Free.

"WHO KILLED CRASSOSTREA VIRGINICA: THE FALL AND RISE OF THE CHESAPEAKE OYSTER" A look at the problem through the eyes of scientists, watermen and oyster farmers. A discussion follows. Noon at the National Museum of Natural History, Baird Auditorium, 10th Street and Constitution Avenue NW. 202-633-1000. Free.

"24 CITY" AND "CRY ME A RIVER" The films examine environmental changes in China. 7 p.m. at the Freer Gallery of Art, Meyer Auditorium, Jefferson Drive and 12th Street SW. 202-633-1000. Free tickets (limit two) will be distributed one hour before showtime.

"BHUTAN: TAKING THE MIDDLE PATH TO HAPPINESS" The people of Bhutan have a unique, environmentally friendly way of living. 7 p.m. at the International Student House, 1825 R St. NW. 202-232-4007. Free.

"CHILDREN OF THE AMAZON" Explore the world's largest rain forest through the eyes of those who call it home. 7 p.m. at the National Museum of the American Indian, Rasmuson Theater, Fourth Street and Independence Avenue SW. 202-633-3030. $20.

"A LITTLE 'JULES VERNE,' " "WILD WAVES," "MOBY DICK" AND "WATERSCAPE" Get wet and wild with four ocean adventures. 7 p.m. at the Library of Congress, Madison Building, Mary Pickford Theater, 101 Independence Ave. SE. 202-707-5677. Free. Seating is limited; call ahead for reservations. Unclaimed tickets will be distributed 10 minutes before the show.

"RENEWAL" Can a religious action help the environment? 7 p.m. at American University, Wechsler Theater, 4400 Massachusetts Ave. NW. 202-342-2564. Free.

"DUMA" A boy and his adopted pet cheetah set off on a ride across Africa. Based on a true story. 10 a.m. at the Avalon Theatre, 5612 Connecticut Ave. NW. 202-966-6000. $5.

"AZUR & ASMAR" Two estranged childhood friends reconnect as adults to find a fairy in this kid-friendly animated film. Saturday at 10:30 a.m. and Sunday at 11:30 a.m. at the National Gallery of Art, East Building, Fourth Street and Constitution Avenue NW. 202-737-4215. Free.

"SPIRIT OF THE FOREST" Animals fight to protect their homes in this animated film. A discussion with the filmmaker follows. Noon at National Geographic Society, Grosvenor Auditorium, 1600 M St. NW. 202-857-7700. $5.

"RECYCLED LIFE" A look at the Guatemala City garbage dump through the eyes of its residents. 1 p.m. at the National Building Museum, 401 F St. NW. 202-272-2448. $10.

"THEY KILLED SISTER DOROTHY" A nun's brutal murder in the Amazon exposes the politics of the forest. 1 p.m. at the AFI Silver Theatre, 8633 Colesville Rd., Silver Spring. 301-495-6720. $10, $9 seniors and students, $6 age 12 and younger.

"WALL E" The box-office hit about a little robot returns to the big screen. 2 p.m. at National Geographic Society, Grosvenor Auditorium, 1600 M St. NW. 202-857-7700. $5.

"BAMA'S JOURNEY," "EYE OF THE LEOPARD," "LIFE IN COLD BLOOD-ARMOURED GIANTS," "IRANI WILDLIFE," "CHINA'S KILLER ZOOS," "RETHINK THE SHARK" AND "THE WHITE WOOD" The day of films begins at 11 a.m. with the story of Alfred Bama's work with orphaned apes and other primates and continues through the story of a unicorn. The films were all selections from the 2008 Wildscreen Festival. National Museum of Natural History, Baird Auditorium, 10th Street and Constitution Avenue NW. 202-633-1000. Free.

"AZUR & ASMAR" See Saturday listing.

"THE GARDEN" The struggles of the participants in the largest community garden in the United States. 1 p.m. at the Avalon Theatre, 5612 Connecticut Ave. NW. 202-966-6000. $10, $7.50 seniors, students and children.

"BEFORE TOMORROW" The effect of Europeans on the Inuit population in Canada. 3 p.m. at the AFI Silver Theatre, 8633 Colesville Rd., Silver Spring. 301-495-6720. $10, $9 seniors and students, $6 age 12 and younger.

"EARTH DAYS" The origins of the environmental movement that began in the '70s are examined in the 3 p.m. screening. A panel discussion follows at 5. Carnegie Institution of Washington, 1530 P St. NW. 202-342-2564. Free.

"DUST" A look at the power of the tiny particles that surround us. 4:30 p.m. at the National Gallery of Art, East Building, Fourth Street and Constitution Avenue NW. 202-737-4215. Free.

"NORA!" A profile of Nora Pouillon, the woman who opened the first organic restaurant in the country. A discussion with Pouillon and producer Sandy Cannon-Brown follows. 6:30 p.m. at the Carnegie Institution of Washington, 1530 P St. NW. 202-342-2564. Free.

"BLUE GOLD: WORLD WATER WARS" Water as a commodity rather than a right is examined. A discussion with experts follows. 7:30 p.m. at the Carnegie Institution of Washington, 1530 P St. NW. 202-342-2564. Free.