That's where I step in; to inform them of the truth in all its ugliness.
Case in point- Columbus Day and Thanksgiving. The truth isn't learned in school.
When I was in junior high school, I asked my history teacher, how could America have been discovered by Europeans when there were Indians already living here? I also asked my teacher why the books don't state that Europeans brought bubonic plague, chicken pox, pneumonic plague, cholera, diptheria, influenza, measles, scarlet fever, smallpox, typhus, tuberculosis, and whooping cough ( my grandfather told me about this) ?
My teacher reported me to the principal who called my mother to come to the school to convince me to apologize to the teacher, and when I asked what I did wrong, my teacher and principal were pissed. And I got in trouble for speaking up.