It didn’t seem like a sound trade, and yet it sounded seamless.

New Roads School music teacher Scott Roewe stepped onto the Moss Theater stage and gave up his shiny brass saxophone to a South American boy in exchange for a repurposed water pipe that had been fashioned with parts of food cans, spoons, coins and old bottle caps.

Then Roewe joined the boy and about two dozen other guest musicians for a rendition of “The Girl from Ipanema,” a Brazilian bossa nova song.

The performance was part of a visit to the Santa Monica private school Monday by a collective of Paraguayan youth who play instruments made entirely of trash.

The group is known as the Recycled Orchestra of Cateura, a Paraguayan town where a massive landfill plays a major role in the local economy. The orchestra has garnered international acclaim and is the subject of a movie called “Landfill Harmonic,” which is currently making the rounds on the film festival circuit.

But the orchestra’s visit to Santa Monica had perhaps a stronger impact than a movie screening could, fostering dialogue and interaction between children from dissimilar backgrounds.

“Part of the experience is showing that the world is really not divided,” orchestra director Favio Chavez said through translator Juana “Kika” Elias, a New Roads language teacher. “With what’s happening in the world, with all of the violence, this demonstrates that kids from different cultures can be united.”

Chavez, who has a long background in music, was inspired to create instruments for the children of Cateura and teach them how to play after working there as an environmental technician.

With help from Elias, Chavez answered questions from New Roads students and invited a handful of them onstage to play with his orchestra.

“Music has a power so big that it can’t only be for musicians,” he said.

His orchestra’s performance was intended to amplify lessons that New Roads middle school students learned during their recent study of Andy Mulligan’s “Trash,” a novel about boys who scavenge from a dump site.

“The Recycled Orchestra of Cateura is close to a real-life manifestation of these fictional characters in last year’s ‘Trash’ reading project,” New Roads Middle School director Alison Miller said. “This experience will help our students remember how lucky they truly are.”

Chavez showed off one of his orchestra’s violins, which are assembled from paint cans, pizza trays and pallet wood. He said some of his group’s instruments can last longer than their traditionally crafted counterparts.

The Recycled Orchestra cruised through a repertoire of familiar tunes, including “O Fortuna,” the “Pink Panther” theme song, Johann Pachelbel’s “Canon in D” and Metallica’s “Nothing Else Matters.”

Chavez said he hopes his orchestra changes people’s preconceived notions about the value of material objects.

“If kids can come together, whether they have so much or don’t have anything,” Chavez said, “then maybe the world might be a little bit better, and it will become more equal.”