You should assume that your students don't know many perspectives on different lifes, nations, cultures, professions, etc. not because they are intolerant, but because how should they know something that they haven't been in contact with their whole lives? So you teach them about the world not because you think they are stupid, but because it is your task to teach them about the world they live in, with the hope that they will make good citizens that in turn are capable of decent choices that create a liveable society for all. You teach them in order to not have them turn into ignorant people.

Political groups that tell you that teaching facts about society and history have the goal of bringing their propaganda into the schools.