That the kids are paying attention is definitely because L&P has gone to school in Germany, which is very different from how school works in the US. That starts with smaller things like there is no dress code for teachers in Germany beyond being presentable. So you can get teachers dressed ranging from sports clothes (sports teachers teaching other classes, who would have thought) over corduroy and very fashionable to pin strip. While it is not that common, you can find some teachers in Germany dressing rather "attention grabbing", making them popular with the pupils, boys or girls, depending the teacher being a him/her. So Sophia is not sticking out all that much on the scale, beside being an insta-hit among the male class members.You must not have gone to school in America because nobody pays attention in literature class...its literally the kind of class you do other homework, browse the internet, listen to music, play phone games, hell even SLEEP, etc.
You'd have to be listening at all for that to happen. The only thing that is UNREAL about L&Ps classroom is how all the kids seem to be carefully paying attention - thats just not reality.
As for the attention thing, it might be normal in the US to sleep in class or play phone games, but in Germany this will land you in hot water. Such behaviour is not tolerated in school, maybe in the worst of worst, but not anywhere else. Especially as there are Mitarbeitsnoten (cooperative effort grades), which are an important part of your grades. You are graded for your efforts during classes, attention, answering questions or making notable comments or ideas. So not being attentive will be bad for you or can even get you thrown out of class.