A Lucky Child: A Memoir of Surviving Auschwitz as a Young Boy by Thomas Buergenthal
Thomas Buergenthal's memoir is the sweetest, least graphic holocaust survivor memoir I've read. He attributes his survival to luck, but he also emphasizes the careful training he received from his parents - both in cleverness and moral strength - and the kindness of many strangers he encountered.
Beuergenthal has devoted his life to Human Rights, and currently serves as the American judge at the International Court of Justice. In his epilogue, he talks about how his experiences through the holocaust and living in post-war Germany shaped his passion to protect others from what he experienced.
This would be an excellent choice for a young teen to read.