Use the Feynman learning technique:
1. Pick a topic you want to understand and start studying it. Write down everything you know about the topic on a notebook page, and add to that page every time you learn something new about it.
2. Pretend to teach your topic to a classroom. Make sure you're able to explain the topic in simple terms.
3. Go back to the books when you get stuck. The gaps in your knowledge should be obvious. Revisit problem areas until you can explain the topic fully.
4. Simplify and use analogies. Repeat the process while simplifying your language and connecting facts with analogies to help strengthen your understanding.
And more specifically for online learning or any learning done outside of an in person course I would say the most important thing is organisation. Give yourself an achievable schedule and put notes in your calendar to block out time, so that you actually stick to it. Also if you are learning about a topic but you don't have any projects coming up where you will implement that knowledge then give yourself a project. If you have a reason to learn then you will be much more motivated.
@Ts. Evaggelos, which of these have you found most helpful to you and why? Thanks.
Use the Feynman learning technique:
2. Pretend to teach your topic to a classroom.
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