Now the "when." During class, students should automatically ke-up every time they go to fighting stance, every time they do a fighting stance turn, and on the first technique of every trip down the floor during basics. During sparring drills, such as two- and three-step sparring, students must ke-up when they have finished their turn so that their partner knows to start. During free sparring, a good ke-up can startle your opponent and gain you a critical couple seconds. We often end class with a series of punches; it is customary to ke-up on the final punch.
Master Marr sometimes jokes with the kids that he is the only grown-up who asks them to be louder. But in all seriousness, being able to free your energy, both physically and vocally, is a huge reason Taekwon-do feels so good for students of all ages. So let loose! Be loud! But refine your ke-up as you refine your kicks and punches: stronger, sharper, faster, and laser-focused.