Scatter some cones (divots) across the area, some the right way up, and some upside down. Split the group into two teams - 'Hackers and Greenkeepers' - and spread them out across the area.
On the word 'Go' the Hackers run round turning the divots upside down and the Greenkeepers must turn them the right way up.
After a set period of time, count the divots to see how many are the right way up and how many are upside down.
Change the teams round and start again.
Progression:
Easier: Reduce the distance between the divots.
Harder: Increase the distance between the divots.
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.