I'm concerned about saying something political that triggers a flood of downvotes, so I'd rather be pretty vague here. One example is their primary US history textbook is kids version of Howard Zinn's People's History of the US.
I have no problem with Zinn's book in general, but I do think it's best read in the context of knowing the "official" version of history. I normally view his book as a useful critique and extension of a classic history text.
To modulate the Zinn book, I simply review with my kids the relevant Wikipedia entries to ensure they have more context. This works great in my family. My concern would be the outcome in a family without engaged parents or radicalized parents, as I mentioned above.
