As part of their study of earthquakes, sixth-grade students learned how to locate the epicenter of an earthquake by triangulation. They used the difference between the P and S waves to calculate distance, and then used that information to draw the circumference around 3 different cities. They located the epicenter by seeing where all three circumferences intersected. When an earthquake strikes, various seismograph centers around the country record the earthquake’s waves. Scientists use this data to learn how far away an earthquake is, but in order to find the direction, they must compare readings from three different seismograph stations.