Traditional undergraduate education often consists of passive delivery of course content without explicit focus on fostering the development of essential skills. However, in recent years, various STEM disciplines have started to place more emphasis on the development of skills and competencies (e.g., Bralower et al., 2008; Cooper et al., 2015). As part of a larger, convergent mixed methods study to examine how spatial thinking skills are represented, developed, and perceived throughout an undergraduate geology curriculum, we have collected daily course observations to characterize the instruction and practice of spatial thinking skills in core undergraduate geology courses. In doing this research, we explore how instructors foster the development of spatial thinking skills in Historical Geology, Mineralogy, Sedimentology and Stratigraphy, Structural Geology, and Geomorphology courses and across the undergraduate curriculum. In this presentation, we will present our results from the course observation strand of our project, including spatial thinking use (instruction vs. practice), type (extrinsic vs. intrinsic and static vs. dynamic), and skill (e.g., penetrative thinking) within and across undergraduate geology courses. These data show which spatial thinking skills are incorporated into different courses and help identify how students may develop spatial thinking skills across the geology curriculum. As part of the larger project, these results can be compared with student performance on spatial thinking skill tests and with student and instructor interviews. While this study initially aims to describe spatial thinking in one undergraduate geology curriculum, the results have the potential to transfer to other undergraduate-serving universities where similar courses are taught. Additionally, the observation protocol used in this study may be useful as a potential tool for future studies on skill development in the geosciences or in other fields.