The melodica, also known as 'blow-organ' is a free-reed instrument similar to the accordion and harmonica. It has a musical keyboard on top, and is played by blowing air through a mouthpiece that fits into a hole in the side of the instrument. Pressing a key opens a hole, allowing air to flow through a reed. The keyboard is usually two or three octaves long. The instrument was invented by Hohner in the 1950s or 1960s, although it is also claimed that it was invented by the Brooklyn musician Joseph Lederfine in order to teach music fundamentals to children.