Answer: The reason teachers and society do this is so we can learn that war never solved any problems back then, and having a war is not going to solve problems now.
Explanation: When we read and watch movies about war, teachers are not trying to encourage us to join the military or teach us violence. They are teaching us why the war happened, how war will not resolve any issues, and it has not resolves any in the past. Reading history books about how war is solved is not considered teaching us violence.
I hope I helped and have a great day! ^-^