Players work in pairs and stand across the court from each other. One player starts with the ball and overhand passes the ball high in the air and then claps their hands over the head and behind their back before the ball comes down.
Once the ball comes back down, the players sets it to their partner, who does the same thing.
By clapping, players have shorter time to prepare for the next pass, just like they will at times in a match. This way they improve their reaction times.
You may ask players to clap more times or even turn around while clapping if the drill becomes too easy.
New hitters rarely miss because of their arm. They miss because of their feet. Build a reliable approach, then time it with your setter.
When your hitter gets stuffed, five teammates standing and watching is how you lose the point. Good attack coverage turns a blocked ball into a second swing.
Coaches spend hours correcting arms in serve receive when the real fault is almost always the feet. Fix the movement and the platform fixes itself.