Even world-class athletes are constantly refining their technique. For years my trainers told me, "Don't A-frame. Be simultaneous." I tried to not let my inside knee drop, but I didn't fully understand my bad habit until I saw myself on video taken at the Battle of the Ski Schools.
In the photo to the right, I'm using too much knee to initiate the turn. This limits my ability to get both skis on edge and make a complete turn or hold on ice or hard snow. Without simultaneous leg action (in which your legs remain parallel throughout the turn with equal distance between your ankles, knees and thighs), shaped skis do not make clean arcs. Here's how to change (see photo below):
To engage two edges, start on flat skis, flexing into your boots and rolling your ankles to initiate the turn. Allow your body to fall into the direction of the new turn. Try pointing the new inside knee in the direction of the new turn like a mountain biker. This will allow you to move onto the ball of the foot of the new outside ski, balance over it and complete the turn on two new edges. If you use your legs simultaneously throughout the turn, you should look up the hill and see clean arcs-like railroad tracks down the snow.
Joey Manley, one of SKI's Top 100 Instructors, teaches skiing in Vail, Colo., and Australia.