In many higher education institutions in countries where English is the second or foreign language; English for Academic Purposes (EAP), English-medium instruction (EMI), Content and Language Integrated Learning (CLIL), and first language-English bilingual modules are attracting interest because of their potential to contribute to the internationalization of higher education. However, it is still not very clear whether students' monolingual, bilingual, or trilingual abilities really influence their academic performance in these modules. This study aims to determine if there is a relationship between participants' academic performance and their type of school attended at secondary level (monolingual, bilingual, trilingual) or age. The total sample of this correlational research was 177 undergraduates (105 females and 72 males, 15-30 years old) who took a university Spanish-English bilingual Biology module at a prestigious Colombian university. Here, we report the results obtained on 2.5 years of data generated by students' quizzes and exams. Independent t-tests showed that the grades obtained in quizzes and exams by the undergraduates who attended monolingual schools at secondary level were slightly lower than those of the university students who attended bilingual or trilingual schools, but there were no statistical differences between them.