Christy Johnson-Lynch of Iowa State demonstrates the drop-step move for passers.
When a ball is served high and over the shoulder's player, they must learn to utilize the drop-step to reach the ball and control it back to the setter. If the serve goes past the player's left shoulder, the player drops her left foot and angles her platform to the setter by bringing it up to shoulder height. Try and keep the arms straight, rather than allowing the ball to get too close to the body and crowd the platform.
Practice these difficult reps every practice so players are prepared to comfortably receive balls served behind and above her.