PBS is a leftist organization. “PragerU Kids is taking on the giant leftist corporations like BrainPOP, PBS, and Scholastic, all of which are left-leaning and promote inappropriate ideas about race and gender to our young children.” -their words. The purpose of education is to teach children critical thinking skills, not YOUR biases.
Other examples are the theories of evolution and climate change. Theories presented as settled science when they are not display the bias of a teacher or textbook, and a debating society or team is where sides are taken and argued, not the classroom, where there is subject matter is to be learned.
For Alexander, nine, learning algebra is part of the process of knowing himself, and I am not there to change him.