Volleyball Drill Demonstration
Players work in groups of 4.
To start this drill one player throws the ball over the net. The player on the other side moves to be under the ball and then bumps it to the player to their right at the net.
The setter then passes the ball to the fourth player who already has a ball.
As soon as the ball is thrown/served by the feeder the fourth player should throw his ball, bouncing once before it reaches them, so that they're ready to serve the ball as soon as the setter has passed the ball back to the fourth player.
This drill can be measured in time or good repetitions.
The reason for using two balls is you can do a vast amount of contacts in a short time; the feeding can be changed to an overarm service when the feeder is a competent server as the emphasis is the passing.
Rotate players regularly to give everyone a chance to work on their game passing skills.