Many students begin drawing an interior by launching in with furniture and windows. It is important to remember that you can manipulate the shape of the room itself. In this example an open closet and a raised floor area to create a visually interesting interior, before the other elements are added. Note the attention to detail in this drawing, with feature wallpaper, shoes and clothes added as finishing touches.
I have done a project similar to this. It adds more rigor if students create their own equations and develop their own design. I usually have them create a certain number of each type of line, have them identify slope, y-intercept, etc. to cover more of what I am teaching on the concept.