I'm not OP, but depending on where in the world you are, classrooms with 50+ students aren't that rare even today: https://www.economist.com/china/2018/09/13/anger-grows-in-ch...

I'm most familiar with China (I taught middle-school classrooms of 55-60 in Yunnan around 2010, and had some friends in Guangzhou teaching 75-80), but I assume there have been & are plenty of countries with similar situations.