Usually a disco consists of two sessions. The first session for the little ones (Kindy / Pre Primary to Year 3) and then the second session for the older children.
The younger session involves a few games (for example - the limbo) to get the children involved. The older children generally prefer to dance straight through and often ask for a slow dance or two.
Music usually consists of current music (what's on the charts) with a few classic hits like the Macarena thrown in for good measure. The kids usually come up throughout the night and ask for their favourite songs.
Most of the time, these discos are held on school grounds or occasionally in a local hall.