One of the [tag]basketball defensive drills[/tag] I like for kids is one I call the Shuffle Drill.
Set up 8 cones on a the court–4 on one sideline approximately just above the free throw line, a little bit below the free throw line, half court, and the other free throw line.
Then the other 4 cones in the middle of the court.
Each player lines up behind a cone. The first player (on the sideline cone) will shuffle to the middle cone. The player in the middle will shuffle to the other sideline and back towards the middle where the first player who just shuffled to the middle will now shuffle back to the original sideline and back towards the middle.
I do this [tag]basketball drill[/tag] a number of times it seems to really helps my kids understand switching and help defense.