Children are taught that information is subjective, and that the Constitution is fundamentally mutable and can be stretched by Congress. There is little emphasis on the genesis of the Constitution and the context in which it was written and changed, and the importance of the document has been lost in recent history.
It is my personal opinion that the U.S. educational system has its flaws. It has become common practice that curriculum is taught with very little advocacy for the integrity of the lessons being endorsed. Our national history has to be scrutinized in order to prove its validity, only then should it be taught.
I learned mostly about the US Constitution during 5th grade Literacy and in 6th grade MN History. I have checked multiple sources and they all say the same thing. I don't think that schools have been misinforming us of our constitutional rights, but depriving us of them (For example, prayer should be allowed in school because of the First Amendment).
We literally read the Constitution. We read the Federalist and Anti-Federalist debate papers (some; there's not enough time in a school day for all). There is no way to teach history without bias, for by selecting what information to teach, we inherently show bias. Our system can teach a lot; how much students retain is another matter entirely. An effort should be made to show balanced views of history, not an (impossibly) unbiased one.