The discussion aims at two objectives. One is for students to understand there is a rotation sensor in the medium motor as well. It works in the same way as in the large motor.
The second objective is to show the difference between a vertical and a horizontal grabber. You can give grabbing a bottle as an example and explain how difficult it would be to catch a bottle with a vertical grabber, as we should have a huge one, and how easy it would be with a horizontal grabber. Nevertheless, if we carry a plate, we should use the vertical grabber as the mission will be almost impossible with the horizontal one.