The school system isn’t wrong in the sense that it’s further from the truth than Karl Popper. It’s wrong like the Catholic Church was wrong in refusing to accept Galileo’s heliocentrism and in locking him up so as to protect their worldview.
We believe that it possible for human beings, through conjecture, reason and criticism, to come to know and understand truths about the world, including truths about the human condition and about specific people, and including truths about matters that are not experimentally testable. We do not believe that we possess the final truth about any of these matters, but we do believe that our successive theories can become objectively truer—with more true implications and fewer errors.