It's an age-old debate in the yoga world —do you teach a pose variation as "beginner variation to intermediate variation to advanced variation" or "intermediate, beginner, advanced" or "advanced, intermediate, beginner?"
I've seen it done all three ways successfully. Most teachers are horrified by the idea of showing the advanced variation first, but one very well known teacher I know uses this format beautifully. When I asked him about it, he said that teaching the advanced variation first keeps him from making assumptions about the ability level of his students and it also challenges them to push their edges. It's a valid point, and when I took his class I found myself successfully trying variations of poses that I might otherwise have opted out of. Granted, he is also a very skilled and knowledgable teacher.
Bottom line, I don't think there is any right way to teach to various levels. I typically teach the intermediate variation, followed by the beginner variation, then I offer an advanced variation. As most of my classes are powerful flows these days, I tend to transition quickly from the intermediate variation to the beginner option and offer the advanced as a, "if you think you want to go there and can challenge yourself safely." It seems to work, or at least my students keep coming back so I assume it does.
I really believe in teaching the intermediate variation first for general vinyasa classes. Too often I see teachers teach only to the beginner, leaving the other students behind. It's a delicate balance between including the new person and keeping your regulars committed. I find that balance lies in taking the time to chat with a beginner at the start of class to decipher their ability level, as well as warn them about the tricky moments they can expect in your flow. It's also a great time to encourage them to take breaks. I have found it helpful to try to place a beginner in the middle of the room (never the front row) wedged between regular students they can look to when they are confused. Let your beginners know it is perfectly acceptable to feel totally and completely lost…it's a new language after all.
Remember your first yoga class? Yeah. Terrifying. You want them to come back, so keep that in mind.
All that said, I make it an absolute policy to teach to my regulars, not to that one beginner. The regulars are the ones who show up for me week after week. For the new person, I offer hands-on assists, direction with my voice (maybe repeating an instruction more than once) or sometimes I just let them flail around. As long as it's done safely, a little flailing never hurt anyone and helps a duckling become a swan.
I design my classes in a way that is most familiar to my background as a dancer—each week we build on what we learned the week before.
Week one lays the foundation of the movement, weeks two and three build on the previous week, and by week four everyone is flowing and moving in a beautiful concert of breath and grace. Yes, I stay with the same flow for a month so students can see progress. If you choose to teach like this, you have to expect that the first week will be a bit of a hot mess, and you must be okay with it. If you get a polished practitioner in your class it will be a real shock to their system, so warn them and they'll quickly join in the commotion. ‘Commotion’ is only a few letters off from ‘community’ after all.
For instance, a few months ago I introduced a new challenging chest opening series that involved a long one leg balance series and some intricate but fun transitions including a moving push-up. I had people falling all over the place—their own mat, others mats, even into the pole in the room. We were all hysterical. But you know what? They brought it back the next week stronger, more polished and calmer. All because I stood my ground and taught to the middle ground. We have a choice as teachers in how we format and teach, and it must mimic your authentic voice. You can't be everyone's teacher, but the ones you really speak to will show up for you again, and again, and again.