Most introductory courses in environmental science are large, lecture-style general education classes. North Carolina State University's ES 100 is no exception, enrolling between 200 and 300 students and holding class meetings in the campus cinema. A key underlying learning objective, however, is to teach students that science is the pathway to discovery. In 2018, I involved my class in a hands-on service-learning project measuring trees on campus. After encountering logistical issues, I engaged students to evaluate and improve our methods. With the help of sustainability and instructional technology grants and expertise, I developed innovative teaching tools and data collection methods to create an enhanced field lab to collect long-term data on more than 100 campus trees. Between 2018 and 2019, students' reflection responses shifted from focusing on processes, like data collection, to more concept- and discovery-themed ideas about urban trees and their health. Further revisions to the project between 2019 and 2020--which mainly included having students use the Tree Benefit Calculator--helped students focus more broadly on the ecosystem services that urban trees provide.