Feynman technique - a simple and powerful way to rapidly learn and retain new concepts.
1. Write down the name of concept you're trying to learn.
2. Explain it in plain English, as if you were teaching it to a new student.
3. Identify things you couldn't explain well, re-read the source material and research them. Try explaining again until these knowledge gaps are gone.
4. Simplify your explanation, get rid of technical terms and use simple analogies. ELI5.