Rather than have them take their eyes off the plane, the technique I find most helpful is to have them put down the buddy box, stand next to me, and have them put their thumbs on top of mine. While we both watch the plane, I put it through the desired maneuvers. This allows them to see the plane's reaction and feel the size and duration of the stick movements. After a couple minutes, back on the buddy box, and they tend to be much smoother.

Brad