Place a few balls on the baseline and spread them out. Players move in and out between the balls, moving as if they were in defence. Make sure players avoid contact with the balls.
This exercise masters footwork skills and the ability to change position quickly in defence.
If you want players to work harder, you can add more balls so that they are turning quicker, or alternatively, have less balls so that players take short steps and control balance.
World Rugby has reportedly conceded Aaron Smith's disallowed try in the World Cup final should have stood.
"It is not only useful for staff who are experienced but a valuable tool for those subject staff who have to take teams."
The variety of sessions across sports - sometimes we steal session ideas from one sport and use them with another.