The challenge for today's elementary teachers is not "whether" but rather "how" to use computers to effectively teach students essential skills and concepts. One exciting way of meeting this challenge is to use Geographic Information Systems (GIS), computer software that captures, manipulates, analyzes, and displays data on specialized layered maps. GIS links together commonly seen map features, such as bodies of water or county boundaries, with information such as pollution levels or population density, making it possible to see relationships that otherwise might not be apparent when viewing a static map. This article presents a study comparing the effectiveness of using GIS-based lessons to traditional textbook-based instruction on the same topic. The study focused on plate tectonics because it is a map-based concept with which many upper elementary students struggle. The lessons were broken into two parts--the first portion focused on volcanoes, and the second on earthquakes. The results revealed the potential of GIS technology in helping students concretely understand abstract concepts while at the same time strengthening students' inferential and problem-solving skills. In addition, GIS technology provided teachers with a new tool for students to use to collect data, expanding students' repertoire of resources beyond websites and encyclopedias. (Contains 5 resources and 4 online resources.)