My Experience in Teaching Physics

by Charles Chiu

Attributes of good physics teachers

Simplicity and Clarity: In the summer of 1995, after participating in an International Conference in Shantou China, I traveled to Shanghai, where I spent my adolescent years and attended a high school reunion of the class of 1957. There were present our high school teachers who were in their 70s and 80s. Among them was my favorite teacher, Mr. Chen. Seeing him I had a flashback to my high school days. Mr. Chen, was standing in front of the chalkboard explaining his methodical way why the water surface near the wall of a glass is concave while that of the mercury surface is convex. His explanation was so intuitive and so clear that his teaching impacted my outlook toward the causal world we live in, and it eventually led me to choose physics as my field. My dream was, among other things, to teach physics like Mr. Chen; to communicate to students the profound truth with simplicity and clarity.

Soon after my high school graduation (1957), I came to the US as a foreign student. I did my undergraduate work at Seattle Pacific College, majoring in Physics and Mathematics and did my doctorate work in High Energy Particle Physics at the University of California at Berkeley. I did my post doctorate work in CERN, Geneva Switzerland; Cambridge University, Cambridge, England; and Caltech, in Pasadena California. I then joined the faculty of the UT Physics Department in 1971.

A steep climb with ease: During this period, my main research interest was in Particle Physics. I also enjoyed attending seminars in other fields as well as popular lectures. I was fascinated by some of the lectures where typically a speaker would begin from a relatively elementary starting point. Through careful planning including the use of analogies and examples, the speaker would "effortlessly" work his/her way through various nuances and would arrive at relatively profound ramifications at the end.

I would like to compare the preparation and delivery of such a lecture to a rock climbing process. One begins at the bottom of a hill. By careful choice of anchor points, and by the skillful application of rock climbing experiences, one works his/her way to the hilltop. The entire process is executed in such a professional manner that, to a bystander it may appear as though the job has been carried out effortlessly. A great physics lecture, usually reflects the speaker's deep understanding of physical phenomenon. The lecturer shares with the audience his/her insights as to how nature works from his/her point of view.

"Know" the audience: In addition to delivering great lectures, a good physics teacher also needs to be closely in touch with his class. Having mastered essentials of physics, the teacher is good at explaining physics from different points of views. He is sensitive to the ability of the class, i.e. what the audience can follow and what it cannot follow. He is quick to adjust the lecture to tailor his explanation to the audience's comprehension level.

Enjoying answering questions: Enrico Fermi was a great physicist and he was also a great teacher. According to stories, he always thanked those who asked him physics questions. He often considered questioners were doing him a favor and he enjoyed answering the physics questions posed to him.

During the first 20 years of my tenure in the UT physics department, I was teaching physics courses at all levels from the introductory courses to upper division courses, graduate core courses, and courses in my special area of research. My goal has always been to explain physics as simply and as intuitively as possible while not compromising the rigor of physics. I often apply the rock-climbing paradigm. I begin from an intuitive starting point, and work my way through the nuances with a steep climb. As I prepare lectures, I often make sure that a substantial amount of "physics" is contained in each lecture, to keep the subject matter relevant, interesting and challenging.

I enjoyed teaching the variety of courses. It was a good way to get an in-depth appreciation of the subject matter. I concur with the common saying, "the best way to learn a subject is to offer a course on the subject matter."

From straight lecture to interactive teaching

Engineering Physics at UT: Engineering Physics has the largest enrollment among the service courses offered by the UT physics department. It is a two semester course. Typically there are about 1000 students per semester. There are about 5 to 6 sections in the on-semester sequence and 3 to 4 sections in the off-semester sequence. This course is meant to give students a basic working knowledge of Physics.

In 1990, there was a need to restructure the teaching of the Engineering Physics course in our Department. Professor Austin Gleeson, then the chairman of our department requested Professor C. Fred Moore and myself to help to coordinate the teaching of the course. Since then I have devoted much of my time to large classroom teaching. I became convinced that I needed to understand our students better, in order to deliver good lectures and to become successful in teaching introductory courses such as Engineering Physics.

Engaging the class: In the early 90s, I followed the conventional approach of giving "straight lectures". I often would pause to pose a question and to solicit comments and answers. Typically there were only a handful of students, the same set of students throughout the semester, who would participate during the question/answer pauses.

There was the "silent majority". I became aware of the fact that often there was a substantial portion of the class who did not follow the nuances presented. Many told themselves that they would sort out the details later. They simply busily took notes throughout the entire lecture jotting down in a verbatim fashion what was on the blackboard.

The lecture should be the time to work on the nuances of physics. I wanted to have the majority of the class actively following my presentation. My ultimate goal was to engage the entire class, to have students think along with me during my lecture.

Interactive Quiz (IQ) Sessions: In the Spring of 1995, in our department there was a general interest in implementing interactive teaching in the introductory courses. There was some interest in the "Peer Instruction" approach of Professor Mazur of Harvard. Several instructors tried out different interactive approaches. For me, I simply interspersed the "interactive quiz (IQ) sessions" during my lecture.

During each session I would first pose a question, which students would work out individually. Then they were encouraged to interact with their neighbors to discuss the physics of the question and compare answers. Regardless of the size of a class, a student always has some neighbors. In this manner we promote the interaction of the full class.

Many students like the interactive approach. This promotes more active thinking during a lecture. Some students told me that the IQ sessions kept their minds alert. And the state of alertness apparently often extends beyond the IQ sessions. It is not surprising, some felt that our class was relatively short compared to other classes.

Classtalk system. There was a network system called the Classtalk system which could facilitate the IQ sessions. It involves wiring the classroom with a network of phone-jack-type ports. A student calculator (with certain specifications) is connected to the network. Each student can enter his/her answers using the calculator. Through a special AT & T grant, the support of UT and the support of colleagues in our department, especially the strong support of Professors Mel Oakes and Austin Gleeson, I supervised the installation of the Classtalk system in two lecture halls in Painter. In the fall of '96, with the cooperation and encouragement of my Engineering Physics class, one system was successfully put in operation. In the following semester, several instructors joined me in using both systems.

The classtalk system is not particularly user friendly. It requires a certain effort at the beginning of the semester to get the students and the instructors used to the system. It requires each student to own a special calculator which costs around $120. Only those instructors who recognize the potential benefit of the system and are willing to make an effort to overcome the initial hurdle will embark on using the system. There have been eight instructors in our department who have used the system. They have worked hard to make Classtalk work in their classes. In all cases, the outcome has been relatively positive.

Instantaneous feed back: Typically the time allocated for an IQ session is about one and a half minutes to two minutes. The IQ question posed is a multiple choice question. At the end of the session, the instructor will display a bar-graph showing students' answer-distribution. Identities of students' answers are kept anonymous.

With this anonymous feature, students are relatively at ease in answering questions. They like the distribution display, which gives them an instant feedback of their work and where they stand with respect to the rest of the class. The distribution also gives an instantaneous feedback to the instructor. Taking into account students' varying comprehension levels, the instructor can fine-tune his/her explanation. Having thought about the IQ question, students are more attentive to my subsequent explanation.

Records on the Web. The class attendance/participation records are posted on the Web. Password protected files are available to the individual students and to the instructors and TAs. Previously a student might feel that a large class was very impersonal: no one knew whether he/she was present, whereas now there is a computer record showing his/her class participation record from class to class. So, the records encourage students to be more accountable in their class attendance and participation.

IQ-library on the Web: Once I began to run the IQ sessions, I realized that it was important for me to develop appropriate IQ questions in order to justify the time that we spend on the IQ sessions during the lecture. This then led us to the development of the IQ questions as the semester progressed. We needed to reformat a significant portion of lecture material in the form of the IQ questions. Many of our IQ questions now have a two-level format. They contain two questions. During an IQ session, faster students after completing their first question can proceed to work on the second question, while slower paced students are completing the first question.

To make the IQ questions more accessible to students, we post them on the Web. There are two IQ-libraries on the Web for the two parts of the Engineering Physics course. They are important course reference materials. They help students to keep up with the pace of the course. We thank the Dean of the College of Natural Science for a curriculum development grant which among other things, enabled us to employ undergraduate assistants to work on the IQ-library.

Rock climbing paradigm at work: I view preparation for each class in the same light as preparation for a rock climbing trip alluded to earlier. Here a selected set of questions from the IQ-library are used as the anchor points by the lecturer in climbing from a height A to a height B. Due to time limitations only a few from the set are used in IQ sessions and the remaining ones are incorporated into the lecture. The use of IQ questions for the Web has the advantage that students need not busily copy down the content of the question. All they need is to jot down the IQ number.

This selected set of IQ questions serves to highlight the lecture. I keep an IQ-log on the Web, which reminds students of the highlights of each class. A quick glance at these questions will help them to review the materials of the previous classes.

To sum up, our interactive teaching approach involves two aspects: First of all, we intersperse our lectures with IQ sessions using the Classtalk system to provide an active learning environment for the students and instant feedback for both the instructor and the students. Secondly, we have our ongoing development of the IQ questions to maintain the quality of the IQ sessions and to cover the highlights of the course. In this manner students quickly zero in on the nuances of physics which they need to master.

Personal attention to students

In teaching an introductory physics course, giving personal attention to students, especially those students who are seeking help is another one of my teaching goals. My aim is to help students to develop their problem solving skills and to improve their study habits. Since the class size is large I use the Web. Some of the explanations I use in one-on-one sessions I also post on the web under "Instructor's Comments". A few examples:

Teaching "how to fish":

It is a common saying that: If you give a person a fish, he will not be hungry for a day; but if you teach that person how to fish, he will not be hungry for a life time.

Quite often, in the middle of a semester a student will tell me that he is puzzled. He has been doing well in homework and yet he failed the exams. This is usually due to the fact that the student does not really understand the basic concepts of physics and the strategies involved in applying these concepts. Often homework problems are similar to examples in the textbook and in the IQ-library. Also, problems similar to homework may have been worked out in discussion sessions. The student may have been able to get by without paying much attention to the physics, except the very final formulas. The perception is that, when the student plugs in the appropriate numbers into a final formula, he or she can "work" out the problem.

I would like to refer to these final formulas as the "ready-made-formulas". Providing a student with a "ready-made-formula" is like giving him a fish rather than teaching him how to fish. Having been given a "ready-made-formula" for a specific problem, the student would get the problem done. Yet for another problem where the situation is slightly different, the student does not know what to do.

Basic concepts and strategies: In solving physics problems, it is important to focus on the basic concepts and problem solving strategies. This is analogous to focusing on fishing techniques. Before doing an actual calculation one should look for the basic concepts and strategies needed to tackle the problem. After completing the problem, one should go back to review in what way the basic concepts and strategies have been used in solving the problem.

We have made up a course summary. It contains a collection of basic concepts and implied strategies. We have systematically removed the "ready-made-formulas". We encourage students to use the course summary as their study companion in previewing the material to be covered in the lectures, in working on homework problems, in reviewing for exams, and using it as a common baseline for informal discussions among peers and with instructors.

Post-test self evaluation: I believe in self-reliance. Students who have done poorly in an exam should make an effort to pull themselves out of the predicament. I offered them the following procedure with which to experiment. First identify those problems which they missed in the exam. For each of these problems, study the relevant course materials. Then close the material and work out the problem. If the student encounters difficulty, he/she should study the relevant material again and continue with the closed book exam until all the selected problems are done.

Next is the crucial step of self-evaluation. My instructions to the students are as follows.

Computerized multiple choice exams: To ensure the accuracy, the uniformity, and the efficiency in grading the exams, we have been using the multiple-choice format for exams, which is generated by the "Homework Service System" developed by Professor C. Fred Moore and his collaborators. I believe that the multiple-choice format can be fair, provided great care is exercised in making up the exam.

It is instructive to use a court case to illustrate the point. Typically a legal situation is relatively complex. There are many nuances involved. A lawyer needs to spend much time thinking about how to pose questions to cross exam witnesses, who are expected to give a "yes" or "no", or a very simple answer. Analogously if a question is well posed, the multiple choice format may be adequate.

For a large class, in grading written exams, the final decision on the grading criteria is usually made only after the grader has looked at the exam papers. On the other hand, for a computerized exam one needs to design the questions with great care. One needs to anticipate how to grade students before the exam is given. To use software development terminology, while conventional written exams require a "rear-end effort", multiple choice exams require a lot of front-end effort.

I have experimented with various ways to make up multiple choice exams looking for more refined methods in grading students' work. Typically we break up each exam problem into several parts. Students are graded on their understanding of the problem, on their methodology and on their work. Monitoring the quality of multiple-choice exams is an ongoing process. I believe that one needs to go over each multiple-choice exam to see whether the specific exam has been properly designed to test students fairly.

Since students' work is graded by the computer, we believe it is important for us to pro-actively seek opportunities everywhere to look at students' written work. This is necessary, at least for some students, in order to properly guide them on their reasoning skills, and on their analytical and numerical work. We make ourselves available to those who seek help. Besides office hours, I am available for outside-of-class contacts, such as the after-class informal time, the instructor's weekly discussion sessions, and pretest-review sessions. There are also TA discussion sessions for students. Both the TA and the instructor may also be reached through email.

A success story. The importance of personal guidance to individual students and helping students to be self-reliant can hardly be overemphasized. I recall in one semester after the final was over, two students came to see me and told me that they appreciated very much my putting emphasis on teaching the "fishing skill" and spending time to work with students' study habits.

They said that they had failed the same course the previous semester. At that time, they were talking among themselves about the possibility that UT was not for them. However, they finally decided that they should give themselves a chance for one more semester and they succeeded.

They went on to elaborate. During this semester, they accepted seriously the notion of changing their study habits. They paid more attention to how to think and how to do self-evaluation, learning from their mistakes. They both ended up earning an A in the course. They said now they felt confident about facing the challenges of the new courses ahead.

Closing: It has been almost 10 years since I accepted the responsibility as one of the coordinators of teaching Engineering Physics in our department. The Engineering Physics course is one of the important courses to kick-off the career of our Engineering students. And it is one of the popular courses for other majors, such as Computer Science. My teaching contribution to UT may be summarized by saying that in addition to striving to deliver quality lectures, I am sensitive to students' concerns and constantly working toward providing a good teaching/learning environment for students both in the classroom and outside of the classroom during their time with me.


Besides teaching, I have been actively engaged in research. The main area of my search has been in Theoretical Particle Physics. In the mid-80s, I also worked with Professor Benjamin Kuipers of the UT Computer Science Department on "Qualitative Reasoning", which is a research area in Artificial Intelligence. At that time I was exploring the possibility of building a physics tutorial system using the technique of Artificial Intelligence.

In the 90s, I researched in the area of Acoustic Agglomeration. Together with a graduate student, I investigated the agglomeration process of dust-particles in the presence of sound waves. Here some techniques in Particle Physics was used. I presented our work at the International Conference in 1995 in Shantou, China and in my class reunion in Shanghai mentioned in the beginning of this article.

My present research interest is in Laser-Plasma Physics. I am affiliated with the Downer-Tajima research group in the UT Physics Department, and am working closely with Professor Toshiki Tajima and his student Sergey Cheshhov on Laser-Wake-Field-Accelerator (LWFA) related problems. Based on our collaborative work, in March 1999 I presented a talk on "Accelerator Physics Issues of a 5 TeV LWFA Collider" at the American Physical Society Centennial Meeting in Atlanta, Georgia.

Since my graduate student days, teaching and research in physics have been the main activities in my professional career . From time to time I have had the opportunity to bring the excitement of ongoing research topics to the classroom and to talk to students about them on an individual basis.

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