This inquiry-based activity designed for the fifth through 12th grade allows students to engage in an outdoor, place-based experience, working collaboratively both in groups and as a class to accomplish the class goal of creating a local tree map linked to student-collected data about each tree. During Local Tree Mapping, students explore the local trees in the yard or neighborhood of the school, while learning basic skills in geographical information systems and Microsoft Excel. Through this activity, students gain a deeper understanding of and appreciation for the role of trees within the Earth's ecosystems, as they collect data on tree type, height, diameter, age, and the longitude and latitude of the trees. An extension activity is described in which students can enter their tree data into a carbon dioxide (CO2) emissions reduction calculator to determine how much CO2 is sequestered by the trees in their research site. Local Tree Mapping provides an opportunity for students to gain inquiry skills in science, mathematics, and geography as they participate firsthand in the collection, analysis, and presentation of real-world data that can be utilized by the local community.