Other historians seek to draw lessons from those actions and thoughts as a guide for decisions and policies today. However, they disagree about history's lessons, and so there are many different interpretations of the past. History became a field of study in many schools during the 1800's. Today, students throughout the world study history in school. They learn about the past chiefly from textbooks but also through such activities as field trips to historical sites and visits to museums.
Most nations require schools to teach their country's heritage as a means of developing patriotism.
History is thus used not only to tell students how their national way of life developed but also to justify and support national ideals and institutions. What historians study The content of history. Until the 1900's, historians primarily studied political events. They wrote almost exclusively about diplomacy, wars, and affairs of state. Today, historians also study many other subjects.