KE'EAU, Hawai'i — Portraits in the school's library are not of U.S. presidents but Hawaiian royalty, from King Kamehameha to Princess Ka'iulani. Near the classroom door rubber slippers are tidily lined up by the students, who go barefoot. The calendar shows it's the month of "Malaki."

Hawaiian language and culture fill the hallways and playgrounds of Ke Kula 'O Nawahiokalani'opu'u Iki and define the mission of the school with the sizable name — Nawahi for short. English is allowed only during the one-hour English class.

A major effort is under way to revive and preserve Hawai'i's native tongue, including so-called immersion schools, marking their 20th anniversary. Courses from math to science are taught entirely in Hawaiian.

The language was nearly wiped out after being banned from schools across the islands for nearly a century. In 1983, when a small group of educators founded a key Hawaiian language revival program, fewer than 50 children spoke the language. Today, the rhythmic, fluid sounds of Hawaiian are used proficiently by more than 2,000 children.

"It's important because I'm the only one in my family who speaks Hawaiian," said Leiali'i Lee, a 10th-grader at Nawahi, one of 23 immersion programs in the state. "I can make a difference and I can revive my language."

While fluency is still rare — just 1 percent of the state's 180,000 public school students attend immersion programs — Hawaiian words are commonplace around the islands, from vowel-filled town names such as Ka'a'awa and 'Aiea to popular fish like mahimahi. There's a weekly radio news report in Hawaiian. Tourists often are greeted in the language even before stepping off the plane. Hawaiian is finding its way into more books and Web sites. And it is taught as a foreign language at many island schools, public and private.

The immersion schools carry this teaching further, of course.

Nawahi, which has nearly 200 students from preschool through 12th grade, was founded in 1994 as a laboratory school affiliated with the University of Hawai'i at Hilo. Students are taught Hawaiian traditions and culture, such as growing sweet potatoes, building canoes and understanding the land.

The school has succeeded despite financial and political challenges, and skepticism about educating in Hawaiian, the only indigenous language in the United States that is an official state language.

Although about half the students are from low-income families, the school boasts a perfect graduation rate, with 80 percent moving on to college, well above the statewide average for public schools.