In short: exercises in catching and throwing close to the lines of the box.
Organisation: every foursome has a ball. Each foursome works near a line. Explain a piece of line of about 15 metres per foursome.
Why these exercises? The catching and throwing of the ball has to take place within the lines of the box or outside the box, provided that the player and the ball do not touch the ground outside the lines. Balls that threaten to go outside the box, for example, must be kept in, which does not require a special technique, but rather a sense of timing. And that can and must be trained.
a ) An exercise for keeping the ball in when it threatens to go 'out'. The ball is thrown in by the regular ballplayer A a little outside the 'box'. The players come from the front along the line and have to play the ball back to the declarer in a small jump (take off on the right side of the line!). Then they have to join the line again. The server throws the ball further and further outside the box. Very soon it will appear that some players, who used to be hardly able to handle a ball thrown 10 centimetres outside the box, are now quite capable of keeping a ball that is a metre 'out' in the box. A matter of timing and a bit of daring.
b ) Same exercise, but now the ball, thrown by declarer A, has to be placed by the players to a second declarer at B (so a quarter-turn has to be made outside the box in the jump).
c ) In exercise a. and b. the players walked along the line, now they come walking straight to the line. Again, handler A throws the ball a little outside the 'box'. The players must try to:
1) keep the ball inside (it doesn't matter how or where it lands), In all exercises below the ball is kept inside with the right side. In all the exercises below, the ball is kept in with the right hand. Therefore, after a while, have the players stand on the other side of the line and continue the exercise as usual to practice keeping the ball in with the left hand.
2 ) Play the ball back to ball handler A,
3 ) pass the ball to a second initiator at B,
4 ) play the ball straight into the field to the row of players at C.
d ) An exercise in jumping. Attacker A1 plays the ball to fellow attacker A2, who stands still just behind the line. Defender V2 has to try, by jumping in front of A2 and without touching the line or the ground on the other side of the line, to throw the ball to fellow-player V1. Or better said: tap, because that's what it actually is. Remember not to hit the ball with your fist! Change function regularly.