When considering how you can connect with The Boy in the Striped Pajamas, you can think about what you and Bruno have in common. Although the story is set during a very specific time and circumstances, there are many common and universal themes present that you may relate to.
Bruno has a lot of trouble with his transition to his new home. If you have ever moved to a new place away from old friends and familiar circumstances, you may find that you have this in common with Bruno. Did you feel alone and disconnected, yet curious and excited the way that Bruno does?
Bruno also has noteworthy relationships with the members of his immediate family. He respects his father very much but also struggles to understand him and is even a little afraid of him. Many children can probably identify with this. He also has difficulty understanding his older sister, Greta, who is going through her own transition, not just with the move but also as she comes of age as a teenager. Perhaps you can identify with this as well.
Also, recall a time when you made a new friend. Bruno and Shmuel quickly become close friends. Even though their circumstances could not be more different, they still find common ground on which to build their friendship. If you have ever made a friend who comes from different circumstances, perhaps you can relate to this as well.
Speaking of larger world events, think about some of the terrible events you may have seen or heard on the news. Whether there is war, natural disasters, poverty, etc., real people are involved in this and are just trying to live their lives. What makes The Boy in the Striped Pajamas so powerful of a story is that it involves otherwise ordinary children living through extreme situations. I am sure you can imagine that such things still take place in today's world.