"Frere Jacques" is a traditional French nursery rhyme, and this is the Round version of the Song since it is frequently sung in this way. One child or group will start singing the melody, and then a second child or group will join in 2 bars later, and so on. If there are sufficent children or groups then four separate parts can continue to sing the round, each unit starting again at the beginning of the song after they have reached the end. The standard (non-Round) version of the song is available at this link: Frere Jacques.
You can play the mp3 file and see the sheet music if you scroll down the page. The PDF sheet music, Midi and Mp3 files can be downloaded using the links in the left-hand menu. This version of Frere Jacques is in the key of F and it has 2 parts. A fun version of Frere Jacques in the key of C with 5 parts can be seen in this video:
Here is a video of Frere Jacques in 4 parts as a round:
The audio controls below allow you to play the mp3 version of Frere Jacques in 4 parts as a round or you can download the MP3 file. You can also download the midi version of Frere Jacques in 4 parts as a round.
The image below is the first page of the sheet music, and here you can download the full sheet music for Frere Jacques in 4 parts as a round in PDF format.