Learning is a messy activity.
It is the opposite of a deterministic process where the output is determined by the input. But curricula are often designed with this "algorithmic" view of learning. 'OK, first we do this; make no mistake, and do this, and make no mistake with that either.'
Actual learning is more like: what happens if you do this? what happens if I push this thing and wait for something to show up, and what if this, what if that?
To my knowledge this is what my two year old daughter does. She just goes around and does stuff. Chaotic, complete mess. She will sing a song, and it's all the wrong words all the time in the wrong order, and then all of a sudden she knows the song. She tries to put her pants on and her legs end up in the same hole, tries again and it's the other hole. And then one morning she knows how to do it. She learns it gradually, but not orderly. It's a mess from the beginning, but not to the end. In the end, it's smooth and clean.
We assume that because it ends up smooth and clean it should start that way. But smoothness, clarity, success — all of that emerges from mess. It's similar to how the order of a rational society emerges out of the (messy) individual decisions of its citizens. Order from chaos, that's learning.