This version of 1 vs 1 allows players to play in a tight space. The small space allows them to start developing puck protection instincts, winning 50/50 races for pucks, and how to take pucks away. There is really nowhere for players to hide so they have to be engaged.
View the diagram and animation to show you how the playing areas can be setup. The coach will have the pucks just outside the box with players split up on both side. Try to match players of similar ability together. The coach will throw a puck into the box and the next to two players in line will play 1 vs 1. Once a goal is scored the coach plays a new puck into the box and the next two players go.