This study investigates the uses and errors associated with the words in and on in academic writing. Research was conducted by extracting 2,000 samples from student academic writing through the corpus, MICUSP (Michigan Corpus of Upper-Level Student Papers). Native English speakers wrote half of the student samples and non-native English speakers wrote the other half of the student samples. The samples originate from a variety of disciplines and text types (e.g., report). Through analysis of the student samples, this study finds that in and on occur at different frequencies. In fact, in occurred 81% versus only 19% for on. The results from this study show that prepositions occupy the significant majority for the types of uses for the two words at 95% for in and 92% for on. No significant variations exist between native and non-native writers. Thus, second language learners successfully use in and on in academic writing like their native counterparts. Errors with in and on are isolated to prepositional uses for both words with the exception of two outliers including particle use and another use. Within the prepositional errors found, choosing the wrong word (e.g., preposition) was the most common error for non-native speakers. In addition to analyzing the uses and errors, this study includes three lessons with multiple activities in order to aid EAP (English for Academic Purposes) instructors in incorporating corpora into their curricula. The lessons provide samples from MICUSP and intend to offer activities to enhance student comprehension of the varying uses of in and on in academic writing. The lessons may be directly applied or tailored to an individual EAP course.