The following text about the Feynman technique has been taken from https://sketchplanations.com/feynman-learning-technique (Thanks Jono)

Further down you can read my thoughts.

Richard Feynman was one of the great scientists of the 20th century, making significant contributions to physics and other related fields. Part of what made him stand out was his gift for teaching. He had a remarkable knack for explaining some of the most complex things in ways anyone could understand. He was also a model of the desire to deeply understand how things worked, often deriving a result in several ways to be more confident he was right.

The Feynman learning technique is typical of how he approached understanding something deeply and helps explain some of his teaching skills.

1. Spend time writing about a topic as if explaining it to someone.
2. Then practice explaining it, speaking and drawing as if you were a teacher at the front of the class. You may figure out some other aspect wasn’t as clear as you thought and need to look into something.
3. Refine any gaps you reveal until you can share the topic fluently and clearly.
4. Then, simplify your language by replacing complex words and ideas with simpler ones and considering analogies to help people relate.

Now, you can explain it because you deeply understand it, too.

My experience

When I started teaching German I hadn’t heard about the Feynman technique, but I used it unwittingly.

I remember it vividly, in my first adult education German class students thought they had spotted a mistake in the book. I knew the book was correct but I didn’t know why. I told my students I would explain it next week, then ran home and checked all the books I had (this was before we had internet). Ah yes, it was grammar I had learned at school many years ago and I had to relearn it again as I had forgotten all of it.

This is how eventually my online courses came about. I had to explain grammar to students but sometimes didn’t really know how to explain it. Textbooks weren’t always helpful either as they explained things too complicated with lots of difficult words.

So, I learned as much as possible about a grammar topic and then explained it in my own words, trying to explain things as simply as possible. The result is a collection of online grammar courses that go back to basics.

My suggestion for German learners

Next time you’re stuck with a German grammar problem and there is nobody you can ask, follow the Feynman technique.

1. Spend time writing about that grammar topic as if explaining it to someone.
2. Then practice explaining it, speaking and drawing as if you were a teacher at the front of the class. You may figure out some other aspect wasn’t as clear as you thought and need to look into something.
3. Refine any gaps you reveal until you can share the topic fluently and clearly.
4. Then, simplify your language by replacing complex words and ideas with simpler ones and considering analogies to help people relate.

As a German learner you might like to know that there is a German term for this ‘lernen durch lehren‘ (learning by teaching).

So, go ahead, learn German grammar by teaching it to yourself.
And if you’re still stuck, you can still ask me or one of my courses 😉