This document provides an introduction to geography for secondary school students. It defines geography as the study of Earth, including both the physical environment (nature) and human environment (human settlements and activities). It emphasizes that geography is important because it allows for the long-term survival of humans on a planet that we cannot yet escape. The document uses a fictional alien's exploration of Earth to illustrate the difference between the natural and human environments. It includes some key thinking questions, definitions, and an activity for students to practice distinguishing the two types of environments.