Tectonic plates

I don't know where they got this idea:

Sixty percent (60%) of Americans with children in elementary or secondary school say most school textbooks are more concerned with presenting information in a politically correct manner than in accuracy. 

And there is an interesting gap between the public in general:

Thirty-one percent (31%) of adults say most school history textbooks portray American history accurately. But 43% say most U.S. history textbooks are not accurate, and another 26% are not sure. 

And those who have actually read the textbooks, AKA people with kids:

Again, those with children currently in elementary or secondary school are even more skeptical. Just 28% think most school textbooks portray U.S. history accurately, while nearly half (49%) say they do not. Twenty-three percent (23%) aren’t sure. 

 By the way, there is an interesting correspondence here. The approximately 30 percent who say they trust the textbooks and the the mid to high forties range of people who don't. Those numbers correspond to the number of Americans who self identify as liberal and conservative.