Three rebounders all stand inside the key.
The coach tosses the ball up for the 1st three players to battle for the rebound.
The player that catches the ball is the attacker the remaining two players then try to stop the attacker from scoring.
Once a shot/ tackle has been made the attacker stays where they are whilst the other players swap for two new ones.
Four players standing still make every ball handler's job harder. Teach V-cuts, L-cuts and back cuts so your team gets open and punishes defenders who overplay.
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.