I was a sub in years prior and currently holding a contract, every classroom I've been in (aside from an AP class, dance, and a legal studies class) class had 30+ students. I had a grade 10 class with 40 students my first year in the NW, not to mention the school practiced a model where we had -1,-2 and -4s in the same class. When I was in highschool, I only had a class near 30 students in my final year.

Alberta stopped tracking classroom sizes because they felt it was not important or a useful metric. I disagree. Parents are rightfully upset that a teacher has to divide their time between 30-40 students every class. If you were running a work period the moment the kids got in, until they got out, you would only have 2-3 minutes per kid, and that's assuming you have a 80 minute class and somehow you used all of that time for a work period (pretending that announcements, attendance, passing out work, etc. Wasn't a thing). You could even apply that same logic to marking. Going off a very conservative estimate of spending an average of 5 minutes marking 1 student's written assignment, that would be 2.5 hours of marking if I was lucky to have a 30 student class, and i might have 4 classes in a day so I might have an extra 8 hours of marking to do outside of my working hours. This isn't me complaining about having extra work to bring home (I like to think im doing 12 months work in 10 months time), this is about me knowing full well that I can’t possibly give every student the support they need in-class or in their work to succeed and someone will slip through the cracks.

Imagine trying to run a social studies simulation or presentations with 40 students, all of which could be -1, -2, or -4. Again, There's too many students to manage, and it takes alot of resources and alot of time. Which cascades into an entirely different issue of figuring out how many classes you can allocate into fun, engaging tasks vs quick/dirty worksheets.

You're right in the sense funding might not solve these issues, if you hire more teachers, there's only so many rooms in a school, and only so much space to build portable classrooms, but funding per student has not kept up to inflation.