Since this novel is about the Holocaust, you should not have too much trouble describing three historical insights.
A word of caution, however. This book is not historically accurate. It is fiction. Some Jewish leaders have harshly criticized the novel for its inaccuracies. For example, Auschwitz was surrounded by electrified fencing so it is highly unlikely an 8-year-old boy would have been able to crawl under a fence. Also, it is doubtful that there would have been a boy prisoner there of that age. The children were either shot or gassed because they weren't useful for working. Other criticisms of the novel maintain that it gives the false idea that people of the surrounding areas had no clue what was going on in the death camps. The burning bodies could be smelled for miles around, so it is not credible that no one nearby knew what was happening at the camp. Further, with the "final solution" being implemented not only in Germany but all over Europe, it is unlikely that even an 8-year-old boy would not have known what a Jew was. Plus, do you think it is believable that even an 8 or 9 year old would mistake the word "fuhrer" for "fury" -- not knowing that Fuhrer was the name of the leader of his country? Highly unlikely.
Perhaps what you can describe, then, is the historical inaccuracies of the novel. If you do a little research into the Holocaust, it won't take you long to find other points similar to the ones I have outlined.