These short YouTube videos make it very easy to learn things. You might not get a quality education. And you might get more of a cliff’s notes version, but you learn things. And if it’s interesting for you, you can use it to learn more about things in general.
Such is the case surrounding trying to figure out what “sea level” is.
Or you can also watch this video that explains why rivers have bends:
Once you can get past the terrible narration, you can appreciate the absolutely terrifying nature of this whistle. It’s theorized that these whistles were used to strike fear in the enemies. Or to send send the human brain into the next state of being.
I guess when you don’t have metallurgy, or guns, or those fun things, you have to make your own strange things to pass the time.
This video is somewhat easier to watch because the woman can carry a conversation better:
She also has a collection of whistles to blow though and terrify you with.