Arrange the players in a large circle. All the players walk or skip around the circle as the music plays. When the music stops they rush to form groups or small circles of a number given out while the music is playing e.g. when the music is playing the leader calls out 'Fives'. The moment the music stops the players form groups of five. Any one unable to find a place drops out.
Music player
Any number of players
Make sure to explain rules clearly before starting. Divide players into equal teams for fair competition.