They each stand four feet tall and together they weigh about 100 pounds.
But Frine Medrano, 11, and Jessica Galvez, 10, belt out traditional mariachi songs with the passion and strength of adults.
The youngsters have learned the art of mariachi, a 200-year-old Mexican music form, with professional coaching from teachers in the Mariachi Heritage Society, a nonprofit organization dedicated to teaching the music to children and adults.
Renowned mariachi Jose Hernandez, who was a vocal coach for singer Linda Ronstadt, formed the society a year ago. He rounded up professional musicians to teach, providing students with vocal and instrumental training from some of the best in the business.
Yet the classes are affordable: Students pay $5 per course, or nothing if they cannot afford it. Classes are held at North Ranchito Elementary School in Pico Rivera and at the Los Angeles School of Music in East Los Angeles. There are about 100 students, and society officials stress that the program is not limited to Latinos.
The Mariachi Heritage Society's annual budget is about $35,000, most of which is used to pay the instructors.
Students are asked to provide their own instruments and costumes, but the society also offers financial aid. Students at North Ranchito have formed a youth mariachi group called Los Rayitos del Sol ("Little Rays of Sun") that raises money through bake sales and car washes.
Mariachi originated in the Mexican state of Jalisco as dance music performed by an Indian tribe called Las Cora, which used the native instruments of the vihuela guitar and the larger guitarron , Hernandez said. But the music and instruments varied by region, and Spaniards added their influence when they introduced the European guitar and violin to Mexico.
For Hernandez, who grew up performing mariachi with his father and five brothers, the Mariachi Heritage Society was a way to continue and share a tradition that shaped his life.
"The thing that saved me was the music," said Hernandez, whose family came to the United States from Mexico when he was 3 and lived in East Los Angeles and Pico Rivera.
"We were in 'gang land.' But we had music all the time in our home . . . and the connection with my mother and father. Them being proud of me (kept me from getting into gangs)."
One recent evening in East Los Angeles, 40-year mariachi Gilberto Valenzuela critiqued the vocalists, while Hernandez's brothers Cresencio and Antonio, renowned for their trumpet playing, gave tips.
The words passion , feeling and intensity echoed throughout the lessons. "You have to feel the music," Cresencio told the trumpet players.
"This is . . . from down here," Jose Hernandez added, pointing to his heart.
Frine's rendition of "Los Laureles" garnered praise from Valenzuela for its strength. The song, the Maywood youngster later explained, "is about a flower in love with another flower. But the girl flower closes and the man flower says, 'Please open . . . if you abandon me, I'll kill myself.' "
Like Frine, Jessica had no formal training before beginning the mariachi classes eight months ago.
"They taught me how to sing and say the words right, how to open my mouth and how to breathe," Jessica said. "I like the songs--it makes me want to sing and dance."