Oto jest Kasia!

This is the title of a Mira Jaworczakowa's book, which used to be discussed in the third class of the primary school, and which I got from my mother when I was ten. What might be found interesting is the reason for which I got it, as the school I attended did not choose the book as the one to be read obligatory (unfortunately)...
As far as I can remember, I've always fought with my older sister for no reason, which my mother was, undoubtedly, fed up with. Having tried numerous conversations with both of us, she used the last resort- the book about a little girl named Kasia, who lived in an everlasting argument with her sister. The plot seems to be interesting for any ten-year-old as it excellently illustrates both family and school life of the young girl. Although the ending is obvious- Kasia appreciates the ties of friendship between her and her sister, there are numerous threads which give color to the whole. Having looked through the book, I came across quite a nice passage:
"Kasia pobiegła do swojego pokoju i zaraz posadziła obok siebie na małych krzesełkach lalki: śliczną Małgosię, różowego naguska [whatever it is], Murzynka i misia w czerwonym kubraczku. Będzie lekcja. To są uczniowie, a Kasia jest panią w klasie.
Kasia- nauczycielka wezwała do tablicy naguska. Niestety, nie przygotował na dziś lekcji, więc Kasia bardzo sie na niego rozgniewała. Właśnie zaczynała mu tłumaczyć, jak nieładnie postąpił, kiedy rozległ się płacz- głośny, bezradny, rozpaczliwy..."
I have never asked whether the aim had been reached or not, but I am firmly concerned that I was to draw certain conclusions from the book. I was to put myself into fictitious Kasia's shoes and stop fighting with my sister like cat and dog.. Not to mention the fact that I am currently studying at The Teacher Training College :)