The Melodica is a free-reed instrument similar to the melodeon 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. Melodicas are small and light enough to be carried around. Popular in music education, these have even made it into some jazz music and trock records.