I, for one, will never forget it. I started first grade in 1945 just after the war had ended. Shortly thereafter a couple of soldiers came to the school to show a film to the entire school including elementary school. The film showed the liberation of the German concentration camps, stacks of bodies being bulldozed into mass graves, the ovens complete with partially burned bodies, & the starved survivors. No 6 year old is likely to forget that & I know I never have! Now days there are parental warnings on programs like this when one is watching the History Channel.
I wasn't born until the 60's but my dad made me watch the same film I believe when I was about 8 years old. I have never forgotten it either. I believe the film was called World At War... It was a series iirc. I specifically remember naked skeleton thin people walking around and piles of the dead stacked like cord wood being bulldozed into pits.