[dav_Oz]

Never heard of the "learning zones" as a concept but from my own teaching experience after a while I was aware if I made my lecture too accessible and easy to follow through my students got overconfident and didn't fully engage with the problems I gave them as an assignment.

On the other hand if I deliberately left little things out to later test them, they became more engaged because they knew I only gave them the necessary tools but they had to work out the little things by themselves. The students were more on the edge and this resulted in better engagement overall.

It was fascinating to experiment with it because my expectations of hard/intermediate/easy problems were at times wildly off.

And surely, there are adaptations at play here, if one is used to discomfort in order to learn hopefully the danger zone gets smaller with time. Sometimes I feel - especially for younger folks coming fresh from high school - the zone between comfort and danger is pretty small as they got habituated on cramming which is essentially all danger zone.