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.
Good team defence is five players guarding the ball, not five separate one-on-ones. The shell drill is where that starts, so here is how to teach help-side positioning and rotations from the first week of the season.
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.