Spatial reasoning is one of the most challenging skills to master in the science, technology, engineering, and mathematics (STEM) fields. This article reports the results of a teaching intervention that involved using wooden blocks to enhance the development of spatial reasoning in an undergraduate-level introductory geology course. Wooden blocks with growth rings that mimic folded rock layers and plywood that mimicked horizontal layers were used as aids to teach geologic structures in the fall 2018 and spring 2019 semesters. The teaching intervention was evaluated by comparing the exam scores of students who had taken the course before and after the use of the wooden blocks teaching tool. Comparison of students' test scores in spring 2017 with fall 2018 and spring 2019 showed substantial improvements, a 20%-25% increase in their geologic structure questions. Results from an independent samples t-test also suggest that the new teaching tool was effective in both semesters.