Songs in the key of blue by a three-year old

At 3, Richard Hoffmann can't read or tie his shoes yet, but he can play the works of Johann Burgmuller, his favorite German composer. His secret: colors.

Instead of seeing notes like C or F sharp, Richard sees purple and dark green, and knows their corresponding piano keys. It's a homespun technique developed by his parents -- Annie Wang, a piano instructor, and Heiko Hoffmann, a researcher at the University of Southern California.

Richard played nearly a dozen pieces Friday, including Burgmuller's "L'Arabesque" and German composer Heinrich Kohler's "Polonaise," before a group of nearly 50 at the Pasadena Central Library.

When Wang wanted to teach her son piano last December, she said, she worried that the small black notes in sheet music would be too difficult to read. So she developed a system -- the rainbow piano technique -- in which each piano key and pitch has a corresponding color.