Most introductory science courses are large, lecture-style general education classes. Introduction to Environmental Science (ES 100) at NC State University is no exception, enrolling 200-300 students and meeting in the campus cinema. In 2018, I introduced an inquiry-based, service-learning project measuring trees on campus. After experiencing problems, I engaged students to help improve our methods. With the help of sustainability and instructional technology grants and expertise, I developed innovative teaching tools to create an enhanced field lab to collect long-term data on 100+ campus trees. As a result, students’ reflection responses shifted from focusing on processes, like data collection, to more concept-themed ideas about urban trees and their health. Additional revisions to the project in the third year, having students use the National Tree Benefit Calculator (Casey Trees and Davey Tree Experts 2020), led students to focus more broadly on the ecosystem services trees provide in urban environments. Using inquiry-based approaches in large classes is both challenging and rewarding, and making adjustments can better align to learning objectives. Finally, this service-learning project contributed to NC State’s recognition as a Tree Campus USA for 2018, 2019, and 2020.