Well that's bogus! Most high school students, when challenged by a teacher, will just shut up for fear of being penalized when grading time comes along. It's a rare student who will stand up against a teacher. So what these teachers are practicing probably seems more like intimidation to the kids. And if the teacher comes down hard on one student, how likely would it be that another student has the will to contradict the teacher.
And when the kids express their views, when they offer evidence that they are being intimidated into accepting the party line, they get a whole half page article about how wrong they are, along with a picture of their faces and their names, in the local paper.
I hope they can use this as a springboard for more publicity and are not silenced.