I don't know why all these levels have almost no comments. Probably people, solving them, felt it was all too easy and overlooked the fact, that's it's a tutorial world. And a really good one, IMO!
Sometimes, in a very simple level, I just can't see the path. It happened here. Had to try 5 or 6 times (if not more). After solving I feel ashamed, that I didn't see it immediatelly.