The document explains the day and night cycle caused by the Earth's rotation on its axis every 24 hours. It provides definitions for key terms like axis, rotation, and tilt. It then describes a hands-on activity where students use a globe and flashlight to model how the Earth's rotation results in day and night. By rotating the globe and shining a light on different areas, the students observe that it is daytime for one part of the Earth while it is nighttime for another part. The activity teaches that it takes 24 hours for a full rotation of the Earth.