There are a few different ways to teach this sport. Our instructor is a member of NACSW and uses the method which first teaches the dog to hunt for food and then begins to pair the food with the required scents to participate in the sport.
Alternative methods use the scent right away and teach the dog to target the scent and then reward. Honestly that method makes a bit more sense to me based on the other training that I have done with my dogs. The food/scent pairing seems to me that it could be a distraction later on when distractions would be introduced but it has the benefit of being easy to teach and understand.
Our instructor is great and very passionate about the sport. The food/scent method is working well for Riley and the instructor does have us fade the food quite quickly. I'm not sure what method I would do with Stella as we are working on not sniffing the ground so I would worry that having her search for food would not be beneficial for our obedience training. I probably will wait a while before I do this sport with her anyway as I am enjoying "Riley time". She would love it and we will do it in the future but we have lots of other stuff to work on for now.
Here is a video of Riley working. This is at a campground a few weeks ago.