Calepin and carnet, for me, are more like notepad and are definitely not BE copybook or AE notebook (that's cahier).
However, carnet de notes, as an admin tool in lycées (at least in my lycée in the 80s) used to be a rather large format notebook where students' scores were written in by the teachers. As a delégué de classe (kind of class rep), in Première and Terminale (last 2 classes in secondary), I used to have to collect it first thing in the morning and cart it around with me from class to class before returning it to the admin dept. (run by the CPE at the time) at the end of every day!