Apparently this is semi-autobiographical which means the way Katy is presented as more good and brilliant than anyone else is kind of narcissistic. The go off to school and apart from a prigging "anti-flirting" club they start, nothing much happens. Mediocre boys express approval of them for being "ladylike" and not interested in them. 

They write some poetry and attempt to speak french but there is no mention of things like exams and you have to wonder if they actually learned anything or if this is more like finishing school just making them fit for marriage. There's a lot of housework and being industrious and feeling guilty and taking the blame and hiding your true feelings (Rose is to some extent the opposite of that but not really). And loving children too of course. 

I loved this series as a kid but I think even then I must have skipped the confusing bits. As an adult it's just a curiosity from a very limited past.