I learned about the Holocaust as a very young child. Then when I was 8, I met a survivor with a number tattooed on her forearm. If your daughter can understand a concept of death, differentiate between good and evil, she can start learning about the Shoah. The experience can, some time, be traumatic. I remember my very first visit to the Holocaust museum in Washington DC. At the end of the tour, my friend and I, both grown men, were sitting in the remembrance hall weeping like babies. So, it might be better if she participates in a program specific for her age and shares this experience with her peers.