Hi. I followed your link to the article on Texas state school standards and the following line jumped out at me.

Barton went on to say the state curriculum should ignore the contributions of Anne Hutchinson, a New England pioneer and early advocate of women's rights and religious freedom, and argued that Texas social studies books should discuss "republican" values, not "democratic" ones.

They explicitly admit to trying to change the curriculum for political reasons. This is going to take a while to absorb. Thanks for the link.