Reading Sophie's World is like having a short course in Philosophy class. You'll have a greater understanding of philosophy and later as you reach half of it, you would able to distinguish philosophers from each other. The terribly exciting thing happens in the mid part of the book (in my case, it makes me in denial), you wouldn't want to put it down.
Anyway, I don't want to spoil it so I'll say no more but here's a synopsis of the book:
Looking in her mailbox one day, a fourteen-year-old Norwegian schoolgirl called Sophie Amundsen finds two surprising pieces of paper. On them are written the questions: Who are you? and Where does the world come from?
The writer is an enigmatic philosopher called Alberto Knox, and his two teasing questions are the beginning of an extraordinary tour through the history of Western Philosophy from the pre-Socratics to Sartre. In a series of brilliantly entertaining letters, and then in person, Alberto Knox opens Sophie's enquiring mind to the fundamental questions that philosophers have been asking since the dawn of civilisation.
If you are busy or lazy or both, you can read it on Sparknotes and commentary on the book can be found here
There was a movie and a tv series based on this book.. I shall see it soon.