5th graders weren’t too young to be victims of the Holocaust, so they aren’t too young to learn about it. I do agree that age should be a factor in choosing what materials are used in teaching about it, but if we want to be certain that we will never forget it needs to be open knowledge.
I knew about it very early because some of my family died in the camps (no, they weren’t Jewish; a total of 12 million died in the camps, of which half were not Jewish). When I was in 5th grade we were shown a copy of one of the films made during camps being liberated. It didn’t give me nightmares at all but created a thirst in me to try to understand how a whole country of otherwise good people could allow something like that to happen.
Then I married a man who had been born in an American internment camp because his grandparents were Japanese. He spent the first 5 years of his life behind barbed wire because otherwise good people allowed those in power to do that. No country is exempt from being bamboozled into doing something unthinkable, and I think every American should know what has happened in the past so they can watch out in case it should start to happen in the future.
And if you think America is exempt, ask an American citizen who is also a Muslim what has been happening to people’s attitudes since 9/11.