Using a few water bottles or tees the golf creates the plane of an in to out swing.
One tee is roughly 4” behind and 2” to the right of the golf ball. The second tee is placed roughly 4” ahead and 2” left of the golf ball.
The golfer now is to practice swing through the tees with no golf ball. Slowly we progress to hitting a tee, then hitting the ball of off the tee and lastly hitting the ball off of the turf.