<Snipped quote by Sho Minazuki>
Why? Fighting a shark not interesting enough?
It's more like because no one labels what class they're attending at that moment.
They either forego that entirely, or get fancy with the name like they were writing a new chapter for a novel.
Basically because of this I'm much less inclined on trying to follow the classes at all. I'm sure many of us would agree it gets confusing sometimes. Even if you can keep track of one or two of the students attending the class, do note that there are several characters that attend classes and not just a few. We don't pay attention to the rest because they don't label it, so we don't know if they're in the class.
None of us remember the class rosters off the top of our heads, so we can't rely on that either.
It was fine in Math and all those before, simply because EVERY CHARACTER of the same year group was in that class, we just had to remember year groups. Since everyone was in that class, we didn't have to guess or check whether or not this guy or that other guy was in the class.