How do you teach a horse to rollback correctly?

Teaching a correct rollback begins at a slow pace with the individual components installed as separate, confirmed responses before they are assembled into the full maneuver at speed. The sequence is stop, back, move shoulders, turn around the hindquarters, and depart — and each element should be correct and willing in isolation before the next is added. Begin at a walk: walk forward, ask for a halt, back two or three steps, then open one rein toward the direction of the turn while applying the opposite leg behind the girth to move the hindquarters, allowing the front end to sweep around over the hind end, and then drive forward into a lope departure. At this slow pace the rider can be precise about each element — the backup creates collection and loads the hindquarters, the rein opens the turn without pulling the horse off balance, and the departure is asked clearly after the front end has completed the 180-degree arc. The horse should learn the body mechanics of the turn — how to move its shoulders freely while keeping the hind end as anchored as possible — before any speed is added to the exercise. As the horse's understanding develops and the components flow together reliably at a walk, transition to performing the rollback from a slow trot stop, then from a lope stop, and finally from a full rundown stop. Each increase in pace should only happen when the previous speed produces a fluid, willing, correct rollback without stiffness or hesitation between the elements. Horses rushed to full-speed rollbacks before the mechanics are confirmed at slow speeds almost always develop the jumping, sticking, or wrong-lead departure problems described in earlier questions, because the speed outpaces the horse's physical and mental preparation for the demands of the maneuver.