Sophie, you've just reminded me of Sophie's World which I read and enjoyed as an adult (as I was an adult when it was released) but is, supposedly, aimed at teenagers. It's a clever and unusual book, a combination of a novel and an introduction to philosophy. According to Wikipedia ...
Sophie's World is a novel by Jostein Gaarder, published in 1991. It was originally written in Norwegian, but has since been translated into English (1995) and many other languages. It sold more than 30 million copies and is one of the most successful Norwegian novels outside of Norway. Sophie Amundsen is a fourteen year old girl who lives in Norway in the year 1990. She lives with her cat Sherekan, her goldfish, a tortoise, two budgerigars and her mother. Her father is a captain of an oil tanker, and is away for most of the year.