I edited that post above, but the site won't let me include the changes. It took me too long to get it written. So here's the entire edited post as I've redone it.
Yes, pushing the inside foot/ski forward is a very odd thing to be told to do. One should not ever consciously move that inside foot forward. But it does happen on its own. So confusing, right?
Here are two possibilities of what your instructor may have been asking you to do that you misunderstood. This is fun for me to think about, so thanks for the challenge. Please let me know if either of these is right after you figure this out.
1. Consider the end of the old turn/beginning of the new turn. At the end of the old turn, your downhill foot (soon to become the inside foot for the new turn) is behind the uphill foot.
At the beginning of the new turn that same foot/ski starts changing positions relative to the other foot/ski, so that by the end of the new turn, when you are heading in the new direction, it ends up being the forward foot/ski. Somewhere in the Beginning and Middle Phases of the turn, the switch happens.
--This
switch usually happens automatically, without conscious attention.
--It is not good to consciously make it happen, because moving it forward can easily be overdone.
--If it's overdone, this puts the skier in the back seat.
--So don't consciously move the inside foot forward.
--This
switch of the inside ski/foot changing from being the back ski to being the forward ski naturally happens, even if you concentrate on pulling that inside ski/foot back (wow!).
--This is because the boot cuff prohibits the ankle from bending forward. None of this is obvious.
--Trying to pull this inside foot back from the knee down doesn't result in stopping the switch.
--Trying to pull this inside foot back from the knee down prohibits it from getting too far forward.
--This can also help in lifting the tail, if that is something you are trying to do.
Your instructor may have been simply telling you that the
switch happens (we call it "lead change") without asking you to consciously move it forward.
2. You may have been trying to pull the new inside foot back the wrong way. The right way is to bend the knee in order to slide the foot back, without moving the hip above it back. Maybe you were pulling the inside hip back in order to get the foot below it to move back. If you do this, you will be successful in keeping the inside foot behind the outside foot, which is bad, wrong, and unnatural. The pull-back of the inside ski is not meant to move it back but to keep it from moving too far forward (and to do another thing that's not important for this discussion). If you were moving the inside hip back to move the inside foot back, he may have been trying to fix this by asking you to consciously move the inside hip forward (but not the foot below it).
The inside hip should move forward as the inside foot moves forward. They both move forward, switching thier position relative to the outside hip/foot/ski.
But you are being asked (by me or by your instructor??) to pull the inside foot back. Keep in mind that your purpose in sliding that inside foot back (it may move 3 inches or so) needs to happen independently from what you are doing with the hip above it. Attempt to pull that foot back by bending its knee and sliding the foot backwards, while leaving the upper part of your leg, including the hip, forward.
Has he ever asked you to consciously move the inside hip forward? I'm wondering if that was what he was asking and you thought it was the foot/ski he was talking about.
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Misunderstandings are so easy in ski instruction. It took a lot of words for me to do this explaining. On snow, or at the carpet, there's no time for this many words. Instructors are taught to keep all instructions as brief as possible, and to keep the skier moving as much as possible. This has its advantages, but it also leads to misunderstandings. I've always found the written word to be the perfect place to tease out the confusions. Do let me know if either of these possibilities is what was happening.