TUCSON, Ariz. — Fifth-grader Justin Sotomayor stood at the front of his music class singing a passionate ballad of lost love in Spanish.

"Por un amor. ... Pobre de mi. Pobre de mi. Cuanto sufre mi pecho que late tan solo por ti." ("For a love. ... Poor me. Poor me. How much my suffering in my breast that throbs so alone for you.")

Backing him were classmates dressed in crisp white shirts with black bow ties playing various string instruments and trumpets.

This is no typical elementary-school band class. This is the advanced mariachi group at St. John the Evangelist Catholic School, a Notre Dame ACE academy.

The Tucson students may not fully appreciate the mature lyrics of "Por un amor," but the song is quite familiar. A version of it appeared on Linda Ronstadt's 1987 album "Canciones de mi Padre" ("Songs of My Father"), which remains the top selling non-English language album in American recording history.

The young Sotomayor called mariachi inspiring. "It just brings music to life," he told Catholic News Service. "It's just really fun to do."

"The music itself began as a peasant-style music, folkloric type music, sung on ranches back in the days, years and years ago, in Mexico," said St. John teacher and musician David Membrila. "And it was passed on from generation to generation."

The typical mariachi ensemble includes a five-string, fretless guitar known as a "vihuela"; a standard acoustic guitar; a large bass guitar called the "guitarron"; and violins and trumpets. Vocals are usually sung by all members with occasional solos.

Membrila said the music is performed at many Mexican celebrations, especially those marking life's mileposts -- weddings, birthdays, anniversaries and "even midnight serenades to your wife or to your girlfriend."

"We play for the Mass. We even play for funerals," he said. "One of the kids' mottos is, 'We put the fun in funerals.'"

The music appeared in Catholic liturgy for the first time in 1966 in the Mexican city of Cuernavaca. The mariachi Mass became popular in churches around Mexico and in Mexican immigrant communities. Tucson's Cathedral of St. Augustine has a regular Sunday mariachi Mass.

Daniel Sheehy, an ethnomusicologist and a director at the Smithsonian Center for Folklife and Cultural Heritage in Washington, said there are likely 500 elementary and secondary school mariachi programs in the United States. A "pretty impressive" showing for heritage music, he said.

Mariachi music appears to be "holding its own" in American culture because of changing demographics, Sheehy said, adding that the "force of society tends to bleed into the schools."

At the current rate of growth, Hispanics are expected to make up 29 percent of the U.S. population by 2050, according to Pew Research Center studies. Hispanics of Mexican descent now make up 11 percent of the U.S. population.

At St. John the Evangelist in south Tucson, 97 percent of the student body is Hispanic. Mariachi music is taught in third through eighth grades and is the only music program offered by the school.

"It ties (together) the community, the church, the people here in the Southwest," said Membrila.

For Mexican American children, learning mariachi takes them back to their heritage and strengthens the family fabric, said Sheehy, who authored "Mariachi Music in America: Experiencing Music, Expressing Culture."

He said any ethnic music finds its sustainability first and foremost in the family, which is "the main conservator of such music."

Membrila's children attend St. John, which as an ACE academy is part of the Alliance for Catholic Education run by the University of Notre Dame.

He's not only teaching his own children mariachi but their friends as well.

On this school day, he advised the practicing advance class to "play it like you mean it." Later, he stopped the group in mid song. The tempo was not quite right, so he set the mood.

"Look at it this way," Membrila said. "You guys are a slow mist. You've seen spooky movies, slow mist. You guys are just a mist drifting in. You're not a cloud burst! Just a mist, spooky. You are the spookiness.

"One, two, three. One, ready, and...." The mariachis played on.