Wrap the ball around both legs, once the ball has made a complete rotation step one leg forward and take the ball around that leg. After the ball has made a complete rotation, that leg steps back, then the ball goes around both legs again. This process is continued using both legs.
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.