My experience of teaching general astronomy to a big class of non-major students started when I moved to UMass. Before moving to the UMass, my teaching experience was limited to graduate classes, where students already had a relatively strong background in science and mathematics. Teaching a GenEd course really made me to think hard how to explain astronomical phenomena and astrophysical principles to an audience who does not have a strong background in science and mathematics. I set the goals of my teaching to be (1) to get students interested in the subject; (2) to teach them how science works, and (3) to motivate them to have their own explorations of the subject. To achieve these goals, I have made a great effort to connect the astronomical phenomena to be taught to what the students are familiar with, using examples of daily experiences and simple demos. The aim is to show that science is neither mysterious nor too profound to be understood. By making such connections, I encourage the students to appreciate the beauty of science: the same simple principles that govern what we experience daily also govern the motion and evolution of the astronomical objects that are far away. I also believe that it is important to teach the students that astronomy is not only about beautiful images and fascinating phenomena, but also about the physical principles behind them, and about how scientists make inference based on what they can observe but not touch. Whenever possible, I try to make connections between what they learn and what UMass students and researchers have achieved in the past and are doing now, to encourage the students with the fact that some of the real discoveries were and are being made actually not far from them. For this kind of classes, I think the best way is to have clear electronic presentations, so that all students can see the teaching material clearly. For each lecture, I prepare a detailed note about the main points to be covered and make it available to the students on the class website.
I have been taught two high-level astrophysical courses for astronomy majors, Astro-330 on cosmology and Astro-452 on galaxies. For these classes I believe that the students should understand and grasp firmly the core concepts and principles of the subject matter. The students should also learn how to approach problems and how to construct mathematical models based on the basic principles they have learned. In addition, the students should develop the ability of critical analysis. To achieve these goals, I usually focus on a few key points in each class, explaining thoroughly the underlying principles. I then select a few related problems, some of which may be published research problems, for the students to think how they would approach and solve the problems. Students are then asked to explain their approaches and solutions to the class. I will then present a solution, and ask the students to critically examine the uncertainties in the solution.
On the graduate level, I have taught two courses, one is an elective course (Astro 850) on galaxy formation and evolution, and the other is a mandatory course (Astro 792) on current literature. Astro 850 was developed based on the material of a book `Galaxy formation and evolution' (Cambridge University Press) I have coauthored. I firmly believe that the students should not only grasp the core concepts and principles, but also learn how to apply them to real astronomical problems. I also believe that it is important for the students to learn how to critically assess the uncertainties and limitations in the applications of physical principles to a real problem. I try to achieve these goals by suggesting research papers for the students to have critical reading, and by assigning a small number of real research projects for the students to carry out and to report to the class.
I have been invited to give series lectures at a number of summer/winter schools.