In general, you can expect the following:
Group auditions require participants to learn a short dance routine under the choreographers direction. The group has a brief lesson, and then present the dance to the audition team. After the dance component has been completed, the group will sing a song as a whole. This will be a common song (e.g.. Row Row Row Your Boat, O Canada etc.). Participants may be asked to sing a harmony line as part of the audition.
Smile and enjoy the audition process
Show good behaviour
Trust the directors choices
Callbacks (Round Two!)
At the first round of auditions, the director may ask certain auditionees to return to sing again, read a scene, dance some more or any combination of these at the callbacks. Each individual performs for the audition team by themselves. It is at this point that the auditionees must be prepared with memorized lyrics and melody of the required song. They may also be required to act out a scene from the script. All participants in the callbacks will be given their callback material six (6) days before the callback date to allow as much time as possible for practice and preparation.
Extracted from: Family Matters, A Parent’s Guide to the Magic of Theater