1. Add 2 units. Yourself as group leader, and a unit to command.
2. Run forward for 10 meters.
3. Aim to the left of your current direction and order him to move 10 meters in that direction. He will say "2, move back".
4. Aim 90° more to the left (So you face rear) and order him to move 10 meters in that direction. He will say "2, move left".