Maybe this one. But I didn't get what he is doing😂
Discussion
If I were a teacher, I'd make my students sha256 by hand to discipline them.
That's the one I'd have shared. All he's doing is SHA256 by hand, so to understand what's going on you'll have to learn what SHA256 is and how it works in detail.
https://learnmeabitcoin.com/technical/cryptography/hash-function/#sha256