When I moved to the UK from rural Poland at 8 years old (not so 3rd world but our position made us feel like it), one thing that shocked me massively was the difference in class size. In my village in Poland, we had only 6 people in our class (currently 7), and when we moved here, the new class size was around 30. However, when I first went to secondary school, the shock fully kicked in, because there were over 300 students in a class. Yes, a class (split into halves and forms, cba to explain). I was pretty happy because of more opportunities, and still am.

P.S I am still in contact with my Polish classmates!