The Oscars celebrate the year’s best movies. Yet it was Lady Gaga’s singing that stole the show on Sunday. The outrageous pop star toned down her act to perform songs from “The Sound of Music.” The performance honored the 50th anniversary of the classic movie. Some people were surprised to see Lady Gaga’s simple, elegant performance. After all, she is known almost as much for her antics as she is for her singing. Yet Lady Gaga is actually a classically trained musician who can both write and perform.