Answer:
Proper stage directions are vital in order for a play not only to work, but for the actual message in the play to be properly conveyed by both actors and setting. This is why, when we look at play scripts, or movie scripts, sometimes, they are so detailed as to every step, every position and every location where every single actor, support staff and props will be while filming, or performing.
In this case we have two actors: Sarah and Thomas, as well as Drew who would be part of the support staff. We also have three types of props: Screen, machine and controls. Their order, as per the script that is here, would be:
Thomas: center, facing forward towards the large screen.
Screen: Placed in front of actors on scene.
Sarah: On the left-hand side of Thomas, also facing forward towards the screen
Drew: Facing both Thomas and Sarah from their left side and then moves towards the opposite end of screen, in order to control the machine.
Machine: Stands opposite the screen, and therefore, at the back of both actors. Drew must move from Thomas´s and Sarah´s left side towards the opposite end of the screen.
