Petite leçon: montage provisoire
There are many different ways to cast on stitches, such as the provisional cast on that allows you to knit in both directions. Here is my favourite method, with a hook.
Make as much single crochet around the hook as the number of stitches required and end up with a few slip stitches. Break yarn.
Remove provisional cast on: uncrochet, start with the slip stitches and put the live stitches on needle.
And now you can start knitting on the other side!
And what it the point of doing all that? Well, you can use this technique for example to knit my latest design, Theodora doll, without seams: start at the hips with a provisional cast on, knit the body up and the legs down.