Zone Defence: Get the players to set up a 2 - 3 Zone defence with 2 gaurds at the top and 3 big men at the bottem.
When you have this set up get the other players to pass the ball around the defence and making the defence move.
Make sure the player are moving into the right posistions when the ball is moving around.
once the players have started to get it, allow the offensive players to score and see how the defence goes.
Once the 5 players on defence have gotten the process switch offence to defence.
Rebounding is the least glamorous thing in basketball and one of the most decisive. It is also almost entirely a habit, which means it is entirely coachable.
Good spacing is only the start. The best modern offences teach players to attack the defence's rotations and play in a permanent 4-on-3 - here is how to coach that read.
The ball screen produces almost half of all professional offensive possessions, yet most teams still teach it as a memorised play. The modern approach trains the read - giving players a framework to decide based on what the defence does, not what the coach called.