Players work in pairs facing each other, and with a crash mat by one of the players, who starts on one knee.
The opposite player starts with the ball and underhand passes it to their teammate, who has to dive onto the crash mat and dig the ball back.
Players work on two skills at the same time here: diving and digging. While learning to dive, having a mat softens the contact with the chest and arms.
The player passing should ensure varied passes.
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.