I was at school in the 80s and 90s in the UK and this brings back very fond memories of a highly eccentric Latin teacher I had, who mastered this technique and used it frequently. The other memorable thing about him was how he'd tell us he was going to do some photocopying and head off with no paperwork, only to return 5 minutes later still with no paperwork but smelling of pipe smoke. Some more modern classrooms had…
The young science teacher spent the whole lesson writing from his notes onto the blackboard, while the whole class just copied it verbatim. His only interaction was asking whether everyone had finished, before wiping one-half of the board clean to continue.
The other science teacher had us read from our textbooks all lesson, and his only interaction was to get annoyed when we made so much racket he couldn't read the newspaper. He always seemed the smarter of the two teachers to me.
I got the same grade in both exams.