I found John Boyne's The Boy in the Striped Pajamas on one of those "listmanias" on amazon.com, as I was looking for favorite middle-school readers. Of all the YA books I've read in the past month, this has been close to the top.
The story takes place in Auschwitz, where nine-year-old Bruno moves with his parents and sister. Unlike most stories of the Holocaust, however, Bruno is on the other side of the fence: his father is a high-ranking Nazi officer. After months of wondering who all those people in striped pajamas are at the camp (he can see one small section from his bedroom window), Bruno sneaks over to the fence and meets a boy his age. They strike up a friendship that Bruno knows must be kept secret, even though he doesn't understand what is happening. The story, of course, has a devastating ending.
The book is flawed historically for various reasons. By age nine, for example, Bruno surely would have understood the word "Jew." Perhaps if he were 5 or 6 in the novel, his innocence would be believable; but a nine-year-old is old enough to really be taught to hate. And surely the son of a Nazi officer would have been fed a steady diet of hatred.
But I didn't care. I liked believing that a child could be so pure and innocent that he didn't know what was going on. I liked how he calls Hitler "the Fury" and Auschwitz "Out-with." My own eight-year-old still has moments when he realizes that a word he always thought was pronounced one way is really wrong ("Grape-Grandpa" instead of Great-Grandpa).
I love the perspective of the Holocaust from Bruno's view. This was so different from any other Holocaust novels I've read. I'd recommend this to ages 12 and up, only because the ending is so devastating. I think it would be a great introduction to talking about the Holocaust.