I saw this for the first time on Educating Alice’s blog. I read The Boy in Striped Pyjamas last year after reading The Book Thief (loved it!) by Markus Zusak and Yellow Star (loved it as well!) by Jennifer Roy. I actually found the story believable, despite many others’ objections. I’ve had nine and ten year olds before who have never heard of 9/11. The first time I encountered this, I could hardly belive it, but every family has their own beliefs about how much you shelter or expose your child to. Back then when there was not the media exposure that we have now, and Bruno grew up seeing people in uniform, I do think it is possible, though not typical or likely that he would not know what was going on. Perhaps he just couldn’t allow himself to know what was happening. You read stories of mothers who don’t “know” that their child was being molested by their husband or boyfriend. The human psyche can be fragile and sometimes protects itself to an unusual extent.