So, my daughters school had an Everyday Math for Parent's night in January because we were getting so frustrated trying to help our kids. I would teach her the the wrong way (carry the 1) and she would get the answer right but the problem wrong, because it is about the process. So, now I learned that numbers are not numbers. They are sticks and dots, or blocks of 10.
"Re-package". As for the "answer", as long as they can get it, good- IRL that is. The sticks etc. are in packages of 10 and it's to drive home the concept. As they move up the 10's concept is built upon also.
I'm going to guess 2nd. They do algebra in middle school now though. I struggled with it when I took it as a HS student.
I sent the link in the OP to my kids Principal and she said she has not seen that method in any curriculum anywhere at any level. Tl
Hayden brings home simple algebra all the time, he is in the 1st grade. Good thing because once it gets past x + 3 = 5 I won't be much help to him.
