This lesson is designed to help students understand this year's NHD theme "Exploration, Encounter, Exchange in History." It is a companion to the NHD Theme Sheet on the NHD website. As students read the theme sheet, they discover what types of things make up the three parts of the theme, and organize that information on the worksheet. Examples of how two topics fit the theme are provided, and there is also a page for students to practice fitting topics of their own choice into the theme. Last, there is a page of guiding questions for each portion of the theme to help students fully analyze their topic and create a higher level project.