Go to a used book store and check out some old civics books. Book stores often carry old text books for homeschoolers and collectors. Also, it is interesting to look at the older books written by men for boys.
The way I explained the evolution of freedom in America to my children: We started out with white men from Europe who basically hated each other overcoming their bias towards one another from different European Nations to become Amercians. Then we moved to overcome beliefs of sexual inequality. Then we moved to overcome racial inequality or the inequality of ethnic groups beyound Europe. European Nations have followed our lead. African, South American, Arab and Asian countries - not so much. (In Africa, they are murdering whites and albinos, for example.)
As they got older, I explained to them how the elite use race hate and unconstitutional preferences to divide people so they can get power. How they did it with the White majority in history and how they do it with the “diversity” majority (white women and minorities against white males) today. Actually, my oldest son saw this liberal craziness for himself and asked me if his observations were correct. I just made it clear that we don’t believe in race doctrines about any group even when a racist teacher still does.
I worked for College textbook companies in the early seventies through into the eigthies. I was amazed at the chnges which got incorporated into the texts in just a two year span, over and over again. An example is the ‘evolving’ definition of homosexuality, which was defined in an abnormal psyche text as abberrant behavior, then destructive life style, then alternate life style, then not even included finally in the definitions of abnormality. There were similar ‘evolutions’ of data in History texts and accompanying ‘readers’ used with various Humanities courses. If someone wanted to see the growing influence of socialism/liberalism infecting America, all you have to do is consult the texbooks of the fifties and early sixties as they ‘evolved’ over three following decades. The really pernicious devolution happens when a committee re-writes an old standard text whose author lived in the decades of the Depression and the second World War. During the early eighties, the committee approach to fashioning a PC text became vogue.