Chunk

What is a chunk? 

Chunk is giving meaning or logic to things you learn. For example, a child sees their  mother pointing at herself and say mama and smile. As a start , the child knows a small fact that mama is a nice word and makes that person smile, and another small fact that person points at herself because she is mama. So, the child combines the 2 small chunks or facts into one big chunk which is that person is mama.
It's basically like putting small lessons you learn into one big chapter to a have full understanding of a certain topic.
Or it can be the logic of actions, i.e online gaming. You learn the logic of the game on how to play, how to level and how to move and combine all that chunk into the game logic on how to play it. You start doing these actions easily with no poring over small details

How to form a chunk?

First, Focus, you need to have your undivided attention on the task you're working to on in order to create a chunk. You can't focus if you keep checking your phone every 5 minutes or so.

Second, Understanding, you need to comprehend the HOW of doing the subject you are trying to learn. It is the superglue that helps holding the underlying memory traces together. Just memorizing something without understanding it is like having a piece of puzzle that cannot interlock with anything. However, understanding the subject only is not sufficient as you have to practice it in order to strengthen the memory pattern to create a proper chunk that you can recall later.

Third, Practice, practicing doesn't just help you understand better or strengthens the chunk, it helps you to know WHEN to use the chunk and when not to use it. It helps you to create CONTEXT.

Context is quite important because it's where the top down learning (seeing the big picture) meets with the bottom up learning (chunking), it helps you fully grasp the subject as you understand when to use it and how to use it.

Example: Think of this as a math problem.

You understand how the small steps are done, you practice each small step alone in order to understand how to do it. Then, you practice all the steps together in order to form a context on how to use the steps, why are we using it and when to use it. People usually do the first step only which is the how and that gives them an illusion of competence in learning, they believe they understand it but they don't. They don't know how to put the steps together (the context) and why they are in that order. They have a good grasp on recalling the steps, but they don't know when to use it.

How to avoid illusion of competence in learning?

Researches have showed that the most effective studying ways are recall and self testing.
Read the material you're studying it and recalling it in your brain then re-reading it and recalling it once more is very effective. Self testing after it to find your mistakes and fix your flaws is far more superior to other methods.

Other concepts 

Overlearning: overlearning is continuing to practice after you mastered what you can in a session. Overlearning is valuable as it leads to automacity. Overlearning more than once in a single session is a waste of time. You should only focus on the more difficult material which is deliberate practice.

Interleaving: switching between different techniques and methods to enhance flexibility in switching between chunks to obtain a better master and understanding of the subject.

Einstellung: Sometimes your initial thought may prevent a better idea, solution or even prevent you from reaching it.