English medium instruction (EMI) has been increasing in higher education with broad intentions of stimulating internationalization and cross-cultural learning experiences. This form of education presents opportunities and challenges for teachers and students alike. Key challenges involve various levels of second language (L2) speaking and listening abilities among teachers and students operating in EMI contexts. This exploratory study therefore examines the relationship between the main ideas two EMI lecturers in Sweden intended for their students to learn during lectures and the main ideas that EMI students report learning in the same lectures. Prior to six lectures, the teachers summarized to the researcher the main ideas to be included in the respective lecture. Immediately following the lecture, students provided their own summaries of the main ideas. A keyword analysis comparing the teachers' intended messages and students' reports shows that students may not be recognizing and acquiring the main ideas that the teacher intends. Further analysis distinguished two sub-groups of students: those with self-reported Swedish as a first language (L1) and those with self-reported L1s other than Swedish. A binomial proportion test showed that L1 impacted the amount of lecture main idea key words reported by the students in this study. The paper closes with a pedagogic perspective encouraging EMI lecturers to monitor student uptake on a regular basis and adjust their lecture delivery to support better learning and retention of content delivered via EMI.