If I may add to Chucks comments
Quote You as the instructor should know what a shallow angle of bank looks like.
You as an instructor should know what a medium angle of bank looks like.
You as an instructor should know what a steep angle of bank looks like Unquote
You as the instructor must know the above solely by reference to the natural horizon. In other words if you cannot role into a shallow, medium and steep turns, holding the correct bank angle and a pitch attitude which will maintain level flight by looking out of the windshield than you should not be instructing IMHO.