So I've blogged before about how Harry Potter; in particular I've blogged about how the Sorting Hat is either intentionally destroying the wizarding world or completely incompetent, but also a more general point on the nature of the series.
The first book is unmistakably a children's book; when it came out I was 10, and it was the hottest thing at that time. I was actually in the same grade as Harry Potter when it came out, and all my friends were reading it. Yet in just the same way the 7th book is unmistakably not a children's book. For one thing, the later books are all well over 500 pages. They also touch on such topics as death, torture, and making out.
In children's books it is okay that adults are blundering idiots, that kids get away with nearly dooming the entire world to destruction, and that villains and heroes both time their moves exactly with one another.
Yet in adult books, all of that is inexcusable.
So when characters in the 5th book refer back to the events of the 1st book, they should be able to refer back to them and see how they acted completely oblivious to the existence of magic or of magicians who could perform magic, and how the three kids then lauded as heroes actually came inches from handing the key to immortal life to the most evil wizard in memory.
In Harry Potter and the Sorcerer's Stone, we meet Harry and follow him to Hogwarts where he learns magic, and watch as he tries to uncover the mystery of what is hidden in the forbidden wing and who is trying to take it.