What length skis for beginners? There are two schools of thought on this question, and both work. One is that beginners should start on "normal" skis that are a bit shorter than their eventual full-length skis, just to make them more manageable and less awkward to start out on. Typically, that would mean soft, forgiving 140-170 cm skis for most adults. This is what most ski schools have been doing for many years, since the original PSIA American Teaching Method adopted a "modified graduated length method." It retained most of the advantages of the extremely short skis of "GLM," but started with skis long enough to actually behave like, well, like skis!
Recently, a new breed of extemely short (110-135cm) learning skis has come around, largely due (some may disagree) to the efforts of Bill Irwin of Elan skis. These little skis have real sidecut and they perform incredibly well, even for experts. World Cuppers even train on them for special purposes. But they're designed to help beginners quickly discover the performance of "real skis."
And they work great, IN THE HANDS OF A COMPETENT INSTRUCTOR. They carve like Zorro, and work great for so-called "direct parallel" progressions. But they also fit perfectly into traditional approaches--you can wedge with them, skid them, brake with them, and carve. 5 or 6 years ago, when these skis first came out, I took a bunch of instructors out for two days to see how they worked. First, we just played, at our own level, to see what they were capable of, and what, if any, were their limitations. Skeptical at first, we were all quickly amazed at how much fun these skis were, and at what we could do on them! High speed, moguls, ice, extreme carves, you name it, we tried it, and we were smiling!
Then we explored the teaching/learning capabilities. We tried direct parallel, or perhaps I should say, "direct-carve," approaches. With their tight little sidecuts, these skis respond dramatically to edging movements--a little tipping makes a carved track with a very tight radius. Even beginners, at low speeds, could discover "carving" very quickly--something that used to come only after years of experience and training, with higher speeds and a lot of skill and athleticism.
And we explored "traditional" progressions, too, with wedges, both gliding and braking, and gently steered, brushed turns. The little skis worked great here too! More than great, in fact. They made everything easier, while nearly eliminating the crossed tips and common tendency to try to muscle the skis around with the upper body.
I'm a big fan of these little learning skis. Students learning on them usually find that the awkward, embarassing, or frightening early stages of learning to ski pass much more quickly, and the fun starts sooner. A good instructor has more options with them--the effects of edging in turns are so much more apparent that it makes sense to explore them. They do NOT require a "new" teaching method--but they make all good teaching more effective. Most students can experience success on them more quickly.
But most ski schools and rental shops still have a huge fleet of older, traditional lengths. Fortunately, a good instructor can teach good skiing on anything--even full-length skis. Skills can develop just as quickly on any equipment--it just takes a lot less of it to have fun on the new stuff!