Rapides Youth Orchestra is on a roll. The students are preparing to play concerts at Carnegie Hall and the White House in December. But before then, they’ll compete in the Crescent City Classic National Orchestra Competition on March 23. Later this month, they’ll perform the National Anthem at a New Orleans Hornets game. Classical guitarist John De Chiaro teaches string instruments at three public schools in Alexandria. He says it’s easy to spot the kids who will stick with music.