Ran across a parent whose child was taught by her elementary school teacher that 1 divided by 0 is 0. The parent reached out to the teacher to correct her and that didn't go well. Somehow it ended up with the teacher going to the principal, who after reviewing everything, reiterated to the parent that 1 divided by 0 is in fact 0, and to basically stay out of the way of her kid's education.
People wonder why I have so little faith in our education system.