text: Students have a way of staring blankly when teachers are talking. While the students are not paying attention to the teacher's lecture, the teacher is worrying about how to get the attention of his or her students. But the teacher has no idea how the students are feeling, and the students end up not learning anything. In this common situation, the teacher would have been greatly helped if they knew the emotions of their students. If the teacher knew the students were tired, he or she could have made them do a brain exercise or a warm-up. The teacher could have used a conversation starter or made the class more interactive to gain the students' attention.