Quick Selection for Where
In setting up a scene, the group will benefit from being able to quickly agree on basic set pieces in the Where. During play, more may emerge, but everyone needs a door, a window, something to sit on, etc.
More than one room for various things
A bed can be in: A Hospital room, A Bedroom, Jail, Barracks, A mattress store, etc. So you need a few other objects that show the Audience where you are specifically.
Do not be concerned if a student seems to be straying far from your idea of what should be happening to him or her. When students trust the scheme and have pleasure in what they are doing, they will give up the bonds that keep them from release and full response.