The coach or a teammate places the ball on the floor.
Facing away from the basket, player 1 (attacker) stands in front of player 2 (defender).
Player 1 then picks up the ball and attempts to get into position to shoot.
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.