Comment by paulcarey

This is interesting, but I think there's an implicit assumption here that a particular topic must be covered in depth, at which point its study is completed, not to be returned to.

And indeed, this is way many textbooks are structured. But I see no reason for this to be the case. If topics are covered lightly via an exposition and then subsequently drilled into in depth, the order, and resulting motivation becomes almost a side note.

I say this as I'm currently studying linear algebra via Coursera, and the resource that has become most valuable to me is a Scapple board with a bunch of screenshots, text and arrows. It is this (non-linear) diagram that I return to most often to help internalize and solidify my learning.

In this regard, the order of exposition becomes almost incidental.