I didn't understand a lot about statistics until I taught it.

I didn't understand the rest (of what I needed to know) about statistics till I had to analyze my dissertation data.

The way to remember a joke is to tell it before you forget it.

So learning by teaching good; learning by doing, better. The joke thing is both.

But to learn a foreign language, nothing beats immersion.

Interestingly, British and American sign languages are mutually incomprehensible but ASL and French sign language are not. We Murricans got ours from the French, via (entre autres) Alexander Graham Bell...