Talk About Teaching and Learning:
September 22, 2015, Volume 62, No. 06
Teaching Introductory Classes
When I started my position in the department of physics & astronomy at Penn in 1996, I had never been in front of a class in my life. I was assigned Introductory Astronomy (Astro 001) for my first course, given a book and told where to show up. I figured I knew astronomy pretty well, how hard could it be? Little did I know that a single student can teach you a very important lesson. I had just finished a long discussion on the phases of the Moon. With the wonderful information I had provided, the students would now be able determine the position of the Sun, the Moon and their location on the Earth just by looking at the phase of the Moon. Fantastic! Then she raised her hand. She stated in a very plain and matter of fact voice, “I have no idea what you are talking about.” I must have looked like a deer in the headlights. I was almost paralyzed with terror because, for the life of me, I could not understand why she didn’t understand. Thankfully I was able to stammer through the remainder of the lecture, but I was determined to never get in that situation again.
Astronomy offers a fantastic way to introduce science to non-scientists. People are naturally fascinated by the subject. Hardly a week goes by without some new and exciting astronomy picture or result in the news. The very visual and inherently interesting topic attracts students who have always found astronomy appealing as well as those who figure it is somehow less painful than the other options for fulfilling their Physical World requirement! Whatever the students’ reasons for taking the course, the faculty in the physics & astronomy department are charged with making sure that they graduate with some basic literacy in science.
My problem with the student in my first lecture could be summarized by a comment from one of my colleagues who was faced with a similar situation. He said, “I don’t understand. When I was 12, someone told me about the phases of the Moon. It was simple. Why can’t the students get it?” Here’s the answer. Like many introductory courses, Astro 001 attracts a large cross section of students ranging from arts and English majors to economics majors. Some of the seniors have not seen or thought about an algebra problem since high school and would desperately like to keep it that way. What they are definitely not is a professor with a PhD in theoretical astrophysics like my colleague. The vast majority of Penn students are exceptionally bright and are willing to learn. However, when faced with material which is utterly foreign to all of their prior experience, they exhibit a combination of shock, denial, blame and fear. How do we overcome this?
I wish there were an easy answer, but the bottom line is that it takes time and experience. I have found two things that have at least accelerated my ability to effectively present complex science topics to non-majors. Office hours can provide a window into problems that affect the entire class. Even though I have 100 or so students in the class, only about 15 seem to regularly attend office hours—despite what I believe is a very generous policy of meeting with the students pretty much any time. By spending time with a few students who are both desperate and willing to reach out to you, a lot can be learned. Sometimes it will take me half an hour on a single problem before I can figure out the flaw in their reasoning which is keeping them from understanding. Then the “ah-ha” moment for me comes when I realize what the problem is and how to get them past it. The trick is to remember to incorporate it in the next lecture. My guess is that for every student who comes to your office hours with a significant problem or misconception, there are a dozen more students who have the same issue. How do I know this?
Two years ago I introduced clickers into my class. I figured it was time to move into the 21st century. I work with cutting-edge technology all the time in my research, but I had not made any significant changes in my teaching technology since I switched from plastic overhead projector sheets to PowerPoint (now I am really dating myself!). After a very mild learning curve, I was able to introduce about four “clicker questions” each lecture. The students were told they would get two points for the right answer, one point for the wrong one and zero for a no-show. Class attendance went from about 70% to near 100% overnight! The first test of the effectiveness of the clickers goes like this: Go over a reasonably complicated topic and show them some worked examples. Then ask, “Does everyone understand this? I can go over it again!” Generally, no hands will go up. Next slide–clicker question. When the results come in with 40% of the class getting it wrong, you realize that either they were too scared to admit they did not understand, or they had somehow convinced themselves that watching you do something meant they knew it too. This instantaneous feedback is invaluable in guiding and pacing my future presentations.
Sure, the students hate the clickers. Why? It’s simple; if you grade them, then they are forced to come to class! However, they certainly are aware enough to recognize the value. The last clicker question of the semester is, “Should I use clickers next semester?” 72% say yes.
Like it or not, one aspect of a successful course is keeping the students entertained. Sure, I can show a bunch of really cool pictures of objects in our Universe, but that only goes so far. It helps that I am naturally enthusiastic about the subject. When I talk about a supermassive black hole like the one in the movie Interstellar, I inject my enjoyment of the topic into the lecture and bring the students into the discussion by asking engaging questions like, “Why the hell did Matthew McConaughey choose to go first to the planet with a huge gravitational time dilation effect? I mean an hour down there cost twenty years on Earth! Isn’t Earth about to die?” Then we go on to calculate the effect. The students really appreciate any effort that is made to put difficult topics in terms that they can relate to. When they respond positively, you get more satisfaction from teaching and everyone wins.
I have thought a lot about what I want the students to come away with at the end of my course. For most of them it will be the only formal exposure to science they will have in their lives. Twenty years from now, do I really care or expect that they will be able to calculate the force of gravity on a neutron star or the orbits of the planets around a distant star? That would be completely unrealistic. But they will remember they were able to do it at some point and that science is not magic. I hope I have done my part in producing a scientifically literate electorate who can think critically about topics far afield from astronomy such as global warming. Most importantly, I hope when their children ask them something about science, their answer is not, “I was always bad at science,” but rather it is, “I took astronomy at Penn and I loved it!”
Mark Devlin is the Reese W. Flower Professor of Astronomy and Astrophysics in SAS.
He is a recipient of the 2015 Ira H. Abrams Memorial Award for Distinguished Teaching.
He is also the recipient of the 2010 SAS Dean’s Award for Mentorship of Undergraduate Research.
This essay continues the series that began in the fall of 1994 as the joint creation of the
College of Arts and Sciences and the Lindback Society for Distinguished Teaching.
See www.upenn.edu/almanac/teach/teachall.html for the previous essays.