Optimal learning and a sweet spot for difficulty

Theories of optimal learning show that we learn best when it is not too easy and not too hard.

• The zone of proximal development states that we maximise learning when tasks are slightly beyond what we can do.
• The zone of learnability shows that If texts are too easy, you won't invest much effort in creating a mental model. When it is harder, the struggle forces you to retrieve background knowledge.
• The model of deliberate practice argues that when a skill becomes automatic, we plateau at levels of ability far below our potential.
• Learned industriousness states difficulty plays a role in motivation.

If you're always successful, you won't know what to improve. If you always fail, you won't know what works.

We learn the quickest when the success rate is 85 percent.