Owing to the worldwide pandemic, use of technology and online education has increased. Studies into teachers' experiences in Higher Education indicated that teachers find it hard to monitor their students' progress during online education. Adequate teacher monitoring is essential, since it allows teachers to adapt their teaching strategies to student needs. Therefore, it was investigated what monitoring strategies teachers employed in online education and what challenges they experienced. Interviews were held with 10 teachers. The results showed that teachers primarily monitored students during online guided sessions. A difficulty was the lack of non-verbal and other observational cues that are normally available. To deal with this challenge, teachers created explicit monitoring opportunities by adjusting their course design. In the discussion, recommendations are given to stimulate teacher monitoring, and the potential role of automated analyses (learning analytics) to aid teacher monitoring is discussed.