Just regurgitating what they've been taught in the government schools, I suspect - while not actually being taught history.
Edit to add: I just finished a Jeffery Deaver novel, Solitude Creek, in which a 13-y/o boy, "Donnie," spray paints swastikas on a Jewish man's home. His buddies discuss:
"It's called a swastika," Wes said. "The Nazis used it."
Donnie added, "The Indians did too. I saw a special. I don't know." ...
"Who were they (the Nazis) again?" Nathan asked.
Donnie muttered, "They and the Jews had a big war. ... Couple hundred years ago, I think."
They really are this ignorant, thanks to our outstanding public school teachers.