What we know depends on what we’re taught, and what you’re taught about America in our public schools varies from state to state.  Dana Goldstein led a New York Times team that examined social studies textbooks made for among other states, Texas and California.  History tailor-made for Mars and Venus.  The added information in California is less significant than what’s taken out for Texas, There, students my never know what they weren’t told about African-American achievements, for example.