The purpose of this exercise is to improve your clear motion and form. Build solid foundation for beginners. I suggest that the players spent more time just focusing on their motion until become a new habit, smooth swing clear motion. Once the swing motion get consistence, you can move on using the shuttlecock hang in from the high ceiling, make sure adjust the shuttle right in the middle of your racket face. When hitting the shuttle, make sure the shuttle go straight line. Practice until you have a solid and smooth clear motion.