The thing is...skills do not equate to technique. PSIA teaches skills officially and some different techniques unofficially that vary from person to person, as long as they are presented with words resembling the 4 skills, or now the 5 fundamentals..which are essentially still the same skills as before.
There has been a lot of disagreement in the ranks for quite some time about whether balance should be considered a "skill" like the other 3 skills, or whether it should be 3 skills which result in balance...something like that.
Is it ERP+B or BERP? Is it 4 skills or 3 skills +1 other thing...the other thing being balance?
It has always been rather foggy and there have been personal opinions all over the map about it and theories abounding to make sense out of the balance thing....skill or whatever it is.....
I feel the reason that occurred is because many people conflated the meaning of skill and technique into one and the same thing.. They considered the teaching of "skills" to be equivalent to teaching some kind of technique. And they directly associated specific bio mechanical movements with each of those 3 skills and focused most learning and teaching to be about developing those bio mechanical skills as movements. You twist your legs for rotary, you flex and extend your legs for pressure. You tip your feet side to side...or lean side to side, to create edging. But Balance... balance as a thing like that...does't have a specific movement you can do to actually "do" it. ultimately balance is felt.
I will argue that the conflation of skills and techniques has led to false understanding all over the map about skiing, focusing too much on these bio mechanical movements of twisting, pushing and leaning...making these skills very bio mechanical oriented and much less about ski performance and outcomes; and completely ignoring the specifics of how those skills should be blended together while executing ski technique.
So the balance skill, doesn't quite line up with those...because there is not a nice and tidy bio mechanical movement to associate with balance. So when people are thinking that way, with the skills needing to be associated with specific bio mechanical movements...balance falls off the side to many people as somehow not a "skill"...but something else. Many people have tried to say "hey wait a minute, balance isn't a skill like the other ones, there is no movement I can teach!". "How do I teach balance?". Some folks on this thread now in 2015 have declared that it can't be taught and they don't want to try to teach balance.
So there is a lot of disagreement in the ranks about whether the skills concept should be ERP+B or BERP.
The new five fundamentals actually ironed it out in my mind that Balance is definitely a skill like the other 3 skills. They just spelled it out as two separate balance oriented skills and tried to find a way to express that in terms of some kind of bio mechanical movements that can be taught. They mentioned manipulation of pressure along the length of the ski, and managing pressure bias laterally to the outside ski...both are outcomes of developing balance as a skill.
So clearly PSIA still today feels that balance is a skill and it should be taught in some way. I feel the new 5 fundamentals did try to set in stone that the skills concept is BERP, not ERP+B.
Notwithstanding, none of the skills concept, not before and not now; really expresses the technique needed to obtain good outcomes in those 5 skill areas. So, while balance is felt...and you can't really teach someone what it feels like to be in balance. You don't actually need to teach them that. But you do need to teach them how to make sure you are in balance on the correct part of the correct ski for example, or retaining balance while moving through turn dynamics, etc. That is the detail of technique which can absolutely be taught. Good technique will lead to better balance, not just avoiding falling down, but precise balance where pressure goes to the correct part of the correct ski for the greatest possible time while skiing.
The balance skill, according to PSIA, is about being in tune with with your balance and manipulating according to unnamed technique, such that you manipulate pressure along the length of the ski in some way that is desirable but undescribed, or such that your pressure tends to go to the outside laterally. They don't really call that balance...and actually nowhere do they state that balance is a skill...but nonetheless....those two fundamentals are absolutely going to be mastered when balance is mastered.
So as an instructor how do you teach someone to master their balance? You teach them techniques which are engineered to get them in the ballpark of good balance while skiing dynamically and responding the changing external forces. These techniques involve combinations of movement from the traditional 4 skills, with outcomes that will include many aspects of ski performance, as well as balance to the correct part of the correct ski at every phase of the turn.