How to study? When do you understand the theory?

Must say I havent much studied the course yet, only reading so far.
Difference between reading and study? Reading you just skim the text and hope something keeps sticking in your brain. While studying is trying to get the knowlegde from the pdf-files into your brain.
So by study I mean not that you just can repeat the words of the pdf-files, say it again like a parrot, but actually get it as knowlegde.

But how can you check you understood the theory, that it has become knowlegde?
I guess two ways.
1. you apply it perfectly in your games.
2. you can teach the theory to other players.

Number 1 is obvious, if you can apply succesfully then you have it under your belt.

Number 2 is what I am aiming for. As a chess trainer at my chess club I need to be able to explain those things to my students. So I study the lessons as if I am preparing a chess lesson.
This way I can clasify the theory as knowlegde but the hardest part will be to implement it to my chess play, chess thinking. Will have to play many games to do so and at the same time trying to get ride of my bad habbits which I formed in my 27 years of playing chess in a chess club.

They say that one way to better understand a topic is to teach it, which forces you to fill any gaps in your knowledge and to clearly articulate what you're trying to convey. You don't understand something until you can clearly articulate it. Writing is the only form of thinking worth a damn.

Of course true mastery is determined over the board, in the implementation of your theory, meaning you've identified a situation in which your theory can be applied.

I think I will copy you and start creating lesson notes for myself or imaginary students. Thank you for the idea.

There is no doubt in my mind on that. The best way to really understand something is to teach it.

Having to be ready to answer questions, hard questions, about what you are teaching makes you answer them all for yourself first, which leads to much clearer understanding.

If you try to teach it and fail, or can't answer the questions, then are forced to admit that you don't understand it and you have to go back to study until you do.