We instituted interdepartmental pedagogical and curricular reform across a series of introductory environmental science courses, integrating more field experiences, data analysis, and synthesis. Using quantitative and qualitative methods, we found that the students who took the series of modified courses showed greater improvement in answering more cognitively challenging questions than did the students who experienced an earlier version of the courses. The students attributed their understanding to the fieldwork. In a second year, we used only the new materials but compared students who took two of the courses with a gap between them with students who took these courses consecutively. The students who experienced the gap performed better on questions that tested understanding at the highest cognitive level. Therefore, the scaffolded curriculum with inquiry-based field labs, thematic content, and spacing between courses improved knowledge retention and higher-order thinking.