California law PROHIBITS schools from indoctrinating students in Communism. There are some Red Democrats who want to repeal the law, but it still stands for now.
EDUCATION CODE SECTION 51530 No teacher giving instruction in any school, or on any property belonging to any agencies included in the public school system, shall advocate or teach communism with the intent to indoctrinate or to inculcate in the mind of any pupil a preference for communism.
I suspect that this law is honored more in the breach than the observance nowadays.