Earth science students are expected to master the travel-time curves of the seismic waves generated at the focus of an earthquake and recorded at seismograph stations. Commonly, students are required to calculate the distance to the epicenter and the time when the earthquake took place. However, the typical graph of travel-time curves found in textbooks and Earth science reference tables poses difficulties for students. This article describes an activity that teachers can use to modify travel-time curves to simplify seismology for students.