Most of us live pretty much in cultural isolation. So to tell most 9 year old children that 5 million Jews were murdered might possibly mean as much as describing how many Roman soldiers were killed fighting the Visigoths. So why don't you use the time until they can begin to comprehend such a thing by providing them with context that they can draw upon when the time comes.
There are all sorts of solutions. One I like is to introduce them to Jewish culture; especially Jewish culture in that region of the world. Have you seen Oprah's series on religion that came out a few years ago? Okay, I'm no Oprah fan, but the show on Judaism concentrated on a shul in Budapest. I know them, great people. Contact them (I can help you there) and say you want to come with your 9 year old to participate in service on Saturday.
This isn't the great glorious "Great Synagogue", but a small, I mean tiny, shul hidden in the back of a courtyard in the less attractive part of town. The war history and post war history of the place is amazing and they are trying to preserve and document it. My first service I arrived early and, through a translator, had coffee and a very interesting conversation with an elderly gentleman who I discovered at the end was a survivor. One of my more humbling moments when I got a little red in the face on the subject of the holocaust and the gentleman puts his hand on my shoulder and tells me I have to let go of it. That's when the translator told me the gentleman's story.
When the kids see other cultures as normal, proud, honest and contributory to society first hand, then they will really understand the absolute evil of the Hitler's Holocaust or the equal evil of Stalin's Holdomore or a host of other atrocities. We need more citizens to understand. That which is forgotten, is repeated.
Now I am going to suggest that jmauldinuu need to rethink his/her advice a bit. I'm not trying to be picky or overly critical, but the tone, for me is a bit disturbing.
walking through a neighborhood that became a strictly Jewish
neighborhood during the war, and being quite moved by a description of
how closely people had to live to one another, in terrible conditions.
A conversation might be possible with your kiddo about what does it
mean for a government - or the local culture - to require people to
only live in specific neighborhoods, and where that requirement might
That sounds like you are describing the bad part of L.A. These weren't crowded "bad" neighborhoods they were holding centers for genocide. I always wondered how people today found it so easy to compare one or another politician with Stalin or Hitler.
When you wash down the truth and meaning and horror of it all so much; it becomes much easier I guess.
If you are going to have the discussion.
See where this building ends and the next begins? Draw a line across
the street at that point. Now, cross that line. Son, you just
entered hell. In 1944/45 the Nazi's brought over 70,000 souls in here
with one purpose, to gather them for transportation to camps where
they would be murdered, 20,000 more were locked in houses around town.
While waiting so many died of starvation and disease that they were
stacked like cord wood along the sidewalks. The Nazi's did it all
over Hungary. Before the war their were 300,000 Jews in Hungary. The
Nazi's killed 200,000 of them. That would be the equivalent of killing
every man, woman and child in Lubbock, Texas.
But there were heroes, we are going to visit the monuments to them, so
you know the value of bravely. First stop, the Glass House....
I guess my point is, if your child isn't old enough to hear the truth (I completely understand that) don't sugar coat it, save it for when he is ready and use the time until then to prepare him to fully understand when the time if right.