This is a 9th and 10th grade informational text about the formation of the four zones of the world hundreds of years ago. While reading this text, students should cite specific textual evidence to support analysis of primary and secondary sources, attending to such features as the date and origin of the information. Students should also determine the central ideas or information of a primary or secondary source; provide an accurate summary of how key events or ideas develop over the course of the text, and analyze in detail a series of events described in a text; determine whether earlier events caused later ones or simply preceded them (License: https://creativecommons.org/licenses/by/4.0)