In an asynchronous e-learning, students find themselves all alone in their learning process. This feeling of loneliness results in frustration and loss of motivation, leading to a high drop-out rate. Tracking engagement while the student is learning allows intervention at an appropriate time. Instructors are overwhelmed by data reports provided to them in the online courses. In this work, the researchers proposed a student engagement visualization dashboard that visualizes the instantaneous engagement levels every minute, visualizes trends of student engagement levels, and filters and displays the least engaged learner to address the above challenges. The researchers also evaluated the usability of this visualizer in a controlled experiment and found out that the perceived usefulness by the teachers was high. The visualizer allows teachers to gain insight into the engagement levels of all the students at a glance. It will also allow the teacher to take immediate action.