Chairs are used to indicate where the set would be.
 

Rehearsals on the mostly-bare stage

Amy, the costumer, repairs minor wear and tear between run-throughs.
 

Blocking the chase scene:

This section of the director's blocking notes became the scene below in the actual show. Notice the diagonal line crossing from the left-hand square...that's Aladdin swinging across the set. 'G' stands for guard, and you can see the three guards in the same places as the drawing indicates. The numbers indicate townspeople.

Designing the set
The sets begin as Steve's random sketches and drawings. These are translated into three-dimensional reality by Tom. The flats are painted by a crew of voluteers and the set is dressed by Brenda.