As Thinking Child’s program administrator, making We Will Sing part of her after-school curriculum was a no-brainer for Vera, 25. Through a grant from Children’s Trust, 120 students from Florida City, West Homestead, Redondo and other elementary schools pay a one-time $50 fee to participate in We Will Sing and other enrichment activities for the year.

“What they’re doing with kids is wonderful,’’ Montaner says.

Twelve-year-old Craig Williams has one of those smiles that lights up a room. Last year the Thinking Child student was one of 50 boys who received a scholarship to attend a MCC choral program at the University of Miami called Bring On The Boys.

“He loved it so much that he auditioned for the beginners’ chorus,” says Mendez. “What we loved about Craig is that he has such positive energy. He has a passion, and he has such an angelic voice.”

A Boston Conservatory-trained musician who started piano lessons when she was 3, Mendez is utterly confident in the children’s abilities. “If you pour yourself into something with passion and discipline, you’re going to come out on top,” she says. Asked if Craig could pursue a classical music career, she says, “If he wants to, absolutely.”

The hour grows late. There are a few yawns around the classroom. Still, the energy level in the room is high. The children lean forward in their seats, eager.

“I’m tired,” says one.

“Me too," Mendez replies. “I haven’t slept for two weeks. If I’m still standing, you can too.” She projects high expectations, and they meet them.

“You guys are the only ones I’ve started music this hard on this fast. I’m proud of you.” Mendez raises her hands.

“One, two, ready, and ”

For the fourth time, they launch into Fuego, one of three songs about the elements they will perform in Spanish. The room fills with the sound of children singing in harmony, with the polish and discipline of adults.