Deasy students put on a spring concert, titled "The River of Dreams: A Billy Joel Tribute," at Finley Middle School's Wunsch Art Center on Wednesday.
The 64-year-old "Piano Man" singer and New York City icon showed up just before showtime, and watched the 350 students perform 15 of his songs.
Joel sat quietly in the audience with the other parents.
"I asked him if he wanted to sit in front, but he said he would rather stay in the back so he wouldn't make the kids nervous," Rosen said.
[Newsday, CBS New York]