Historiography means the writing of history based on the critical examination of sources, the selection of particular details from the authentic materials in those sources, and the synthesis of those details into a narrative that stands the test of critical examination. Historiography studies cover chronologically various themes, such as local history, social history, cultural history, economic history, political history, military history, intellectual history, environmental history, and other historical studies. History of education is a study of the past that focuses on educational issues. These include education systems, institutions, theories, themes and other related phenomena in the past. History education includes studies of how history teaches in school or society, curriculum, educational values in events, figures, and historical heritage, media and sources of historical learning, history teachers, and studies of textbooks.