When I was a child, my school in Osaka gave us the lecture about Hiroshima/Nagasaki every summer. (watching movies and slide shows, or listening to the survivors' stories.)
I still remembered those slides that I saw. They were really... hard to see. To be honest, I didn't like the day. But at the same time I could not resist to know and thought about the event.
Now I think that it was great opportunities to think "what A-bomb is and why it had been used?" at my early age (around 6 ~12 years old).
This time, there are a couple of exhibitions in the Hiroshima Peace Memorial Museum. The survivors' drawings and Photographer, Yuichiro Sasaki's photos (he was born in Hiroshima and had taken photos in Hiroshima far more than half of his entire life) They are...speechless. It's open until July. If you (someone) plan to go there, I'd love you to see them and think the events by each individual.
* Photo; in Hiroshima city and Miyajima.