Veritasium
3 HN recommenders · recommended in 3 months, 2015–2021
4:10 · 2.5M views · Mar 12, 2012
Veritasium asks people where a tree's mass comes from, then explains that most of a dry tree's mass originates from carbon dioxide in the air. It combines street interviews with a short explanation of photosynthesis.
HN uses it as the go-to demonstration of how unintuitive mass conservation is, especially in weight loss and burning threads.
4 comments from Hacker News
"Where do trees get their mass?" - this video This was highly enlightening the first time I watched it :)
There's a nice Veritasium episode wherein he asks people on the street where a tree's mass comes from: this video (This isn't just one of those "let's laugh at how dumb people on the street are" videos; it's done explicitly as a learning exercise. His PhD looked at how addressing misconceptions and going from there to correct explanations works much better than simply providing explanations: [LINK] ) I thought of it upon seeing the first chart in the BMJ article.)
An interesting corollary to this is "Where do trees get their mass?" Veritasium has a fun video demonstrating how unintuitive this is: this video
And the reverse biochemical process is equally misunderstood. I used to teach high school Science and everyone thought a tree's mass came from the soil. this video