Build-up to everything they do defensively, 5 minutes every day. They force sideline-baseline. Pass the ball around, coach gives a command, then it's live, the defence transitions the other way on a stop (option - or a change of possession), switch offence and defence.
1) Drive - the on-ball defender runs to touch the closest line, based on how the ballhandler is being forced (halfcourt, sideline - or baseline?).
2) Switch - the offence puts the ball down, the defence picks it up and attacks the same basket, the new defenders can't guard the player that was covering them, communicate and rotate, they have to stop ball first, and the post defender can't leave until another defender takes over the post.
3) Trap - trap the ball on a guard-guard or guard-wing pass (very effective if the guard cuts through), move on the pass not the catch. In a game, double fist means trap first pass.
4) Change ends - the offence puts the ball down, sprints back on defence (and picks up a player who was not guarding them).
See Scrimmage - Whistle.