I’m writing this now because I wrote something which I later realized was wrong. It’s been nagging me, so I’m going to post a correction and leave a trackback to the post in question.
The troublesome quote:
“That gave me practice with individually undoing loops — which wasn’t as hard as I thought it was going to be. Just thread the tip of the left needle into the space where the yarn comes out, then when the stitch is slipped, pull the extra loop out. Not hard…”
When I was attempting to tink (knit backwards/undo loops) very early on, I would place the tip of the left knitting needle into the loop under the working stitch, from the direction that the yarn came from. I realized later after having done this very often that this was randomly messing up the slope of my loops. The loops are supposed to be right-leaning in American and Continental Pic versions of (at least) right-handed knitting. That is to say that if you hold up your work and pull down on the fabric slightly, the leg facing your body should be to the right of the leg farther from you.
If the stitches are left-leaning (near leg on the left), this makes them twisted, and can mess up the flexibility and tension and pattern of your fabric. If you search “tinking” (which term I didn’t know until running a couple of searches), you should be able to find videos on how to undo stitches.
From what I saw, to tink (if you’re right-handed), you put the left needle tip in the loop below the working stitch from front to back (near to far) and right to left. Then once that stitch is secured on the left needle, you pull out the upper loop. This should preserve the proper slope (if you wanted your stitches untwisted, at least), which doesn’t differ at all between knitting and purling, if you’re using either American or Continental Pic methods.
I know, it was complicated to me, too.