I would agree with cdnguy here, asking beginners to flatten or edge a ski is difficult. Controlling the amount of edging that way is a more advanced concept. Some percentage of them MIGHT understand what the heck you mean, but an even smaller percentage will actually be able to execute.
One of the reasons that a wedge works is that its easy to conceptualize. its enough for them to think about just keeping the skis wedged, standing on the inside edges, and shifting weight back and forth between the two skis.
I've been watching this thread closely. I think this is a very important discussion. What happens in the first few days of skiing for a new skier can influence greatly what their skiing will be like for years to come. They can become so afraid, or annoyed by the difficulty, or uncomfortable from the weather, or frustrated from falling down and having a hard time getting back up, etc.... that they don't return to ski again. They could have a great time but learn wedge turn survival tactics which implant into their brains and instincts certain so called "skills" which will impair their ability to progress into higher level skiing. Perhaps they will have to learn to think one way, and then one day a teacher will be telling them to think a completely different way and it will be hard for them. And some bad habits will never go away.
The dilemma of this situation is that we have to show them something they can do on the first day, feel safe and have fun....and at the same time...not show them in way that will be opposite of what they will be doing later. Many people have felt for years that wedge turns are debilitating in this regard. They are functional for a first time beginner, but do exactly what I was saying above that is a problem. IMHO, if we are going to continue to use wedge turns for first time beginners we have to always be thinking about how these skiers will advance this skill to higher level skiing.
I have heard a number of different approaches here. I can't say that I agree or disagree with everyone. I do think its easy for us as instructors to overlook the transition between wedge turns and higher level skiing. We all made that transition years ago. We can switch back and forth between wedge and high performance parallel at will. But a beginner that is trying to make that transition, will have to alter their thinking on a few things. Having our minds as instructors wrapped around this transition is key.
Some people even advocate that a wedge should never be taught anymore. I don't know how I feel about that yet, because I tend to think it makes the first couple of days a bit difficult and frustrating for first timers. So its a dilemma. We show them one way, to get them skiing, then later we tear it down and show them a new way. Whatever we do with the wedge way, we should be trying to implant concepts in their brain that will translate easily and smoothly into parallel turns. it would seem that different instructors have different ideas about what that should be, and unfortunately at this point in time there does not seem to be much firm science to indicate a best strategy here. Which is why I think this discussion is so important.
I think most ski systems (ie, PSIA, CSIA, etc..), focus first on helping a skier to get skiing down the mountain. How fast can we get them on the chairlift and skiing down a run safely and having fun? But how we talk about the wedge and how we get them to think about wedging on that first day, should be very carefully presented with complete planning on our part that in a few days we're going to show them how to parallel turn their skis, so that it all relates back to everything we said and did on the first day while wedging.