Excitement in the astronomical community had been brewing for days. NASA had announced that they would soon reveal new findings that would alter the prospects of finding extraterrestrial life. Although science pundits across the Internet imagined that a signal had been received from an alien civilization, more informed speculation centred on the discovery of a new form of terrestrial life. We would find out at a NASA press conference Dec. 3.
This news triggered a torrent of emails from my Astronomy 101 students. They wanted to know whether I had any inside information about the NASA announcement and, better yet, would we be discussing it in class?
Can you talk about this in class? It’s a question students often ask me, usually in reference to stories currently in the news. In a small seminar course, it’s relatively easy to adjust the curriculum on the fly to follow the students’ interests. In large courses like Astronomy 101, which has 1,300 students and many synchronized components, adjusting the curriculum dynamically is much more challenging. By the time I started receiving emails about the NASA announcement, the course was nearing its end and big changes were not in the cards. Fun as it might have been, I thought, I didn’t have time to be spontaneous.
Then I looked up the time of the press conference. When I saw it, I laughed. NASA, it turned out, was going to be making a big announcement relating to alien life at the same time as my Astronomy 101 lecture on the same topic. Bingo!
When I first started teaching in a university, despite my best intentions, I wound up adopting the “default” teaching paradigm: I, as the teacher, would teach and they, as the students, would learn. Like most faculty, I quickly learned that this paradigm doesn’t work well in practice, that merely reciting facts does not guarantee that students will understand or remember them. Study after study has shown that “being taught” is far from synonymous with “learning.”
Astronomy is full of examples of teaching that does not produce real understanding. Many of the examples concern attempts to dispel commonly held misconceptions. A classic example, documented in the 1987 film A Private Universe, concerns the seasons. In the film, new Harvard graduates are asked to explain the cause of the seasons. Many of them confidently assert that the seasons are caused by the changing distance between the Earth and the sun — farther in winter and nearer in summer. The explanation is rational enough but it doesn’t agree with the facts. Many first-year astronomy instructors have had the disheartening experience of carefully explaining the true cause of the seasons — the tilt of Earth’s rotation axis — only to have the students confidently reproduce their pre-existing misconceptions on the final exam. Learning, we discover, does not automatically result from teaching.
Like many of my colleagues who have adopted modern teaching techniques, such as problem-based learning and inquiry methods, I have come to see the teacher-centred paradigm as a real obstacle to learning. Understanding simply cannot be pumped into brains like gas into a tank. Passive learning through lectures is not particularly effective and, even when it is, learned information is poorly retained. Still, for a host of practical purposes, lectures remain the dominant mode of university teaching. But if lectures are so ineffective, why bother with them? What good do they serve? My own belief is that one of the chief goals of lecturing must be to inspire students to learn for themselves.
The NASA press conference started streaming live on the web at 2 p.m. I showed up at Convocation Hall and put the live feed up on the main screen. Just in case, I also queued up the PowerPoint slides I’d intended to show. I explained the situation to my students: NASA was at this very moment making an announcement concerning the discovery of some new type of life. We would forgo our planned lecture on astrobiology to hear what NASA had to say. I turned on the audio for the live feed and we watched together.
Students have a lot of misconceptions about how science works. They tend to believe that science entails the discovery of immutable laws of nature and their permanent inscription on stone tablets, which are then photocopied to produce first-year textbooks. This is partly the fault of scientists, who toss around terms like “law” too casually. It’s been about a century since Einstein showed that Newton’s law of gravity is only approximately correct. Already we know that the successor to Newton’s law, Einstein’s general theory of relativity, itself falls short of fully explaining gravity. Yet still we teach students about Newton’s “law” of gravity. It’s no wonder they are confused.
“Science,” I had tried to impress upon my students earlier in the semester, “is both provisional and progressive. Many of the things we call laws today will need revision tomorrow in light of new evidence.” I could tell they weren’t getting it. Students often interpret the provisional nature of science too strongly, assuming that it means that all current science is simply conjecture. Perhaps the best way to show students how science actually works is to get them to do some science of their own, to go through the steps of the cycle of science, but that’s difficult in a large class with no laboratory component. Still, the pedagogical difficulties don’t diminish the importance of the point: if I can get my students to understand how science works they’ll be able to perform that beautiful miracle of teaching themselves.
With that in mind, I waited until NASA’s major announcement had been made and then flipped to my prepared slides. I had written that all known forms of life follow the same basic biochemical pattern. This statement, I was able to demonstrate, was now incorrect. The new findings concerned a bacterium that had found a novel way to make DNA, substituting arsenic for phosphorus. Life, it turned out, was not all based on the same biochemical blueprint. Science had progressed and, best of all, it had done it right before their eyes.
I alternated between the press conference and my slides for about half an hour, indicating all the places where my slides would need revision in light of the new findings. The students were able to see that the required revisions, while important, didn’t entail the wholesale abandonment of the existing models. I could not have hoped for a better case study, nor one that would leave as lasting an impression.
After the lecture, I was swarmed by students with still more questions. Many of them went home and did their own follow-up research, posting the results to the Astronomy 101 online discussion board. The story of this discovery, it emerged, was less cut-and-dry than the NASA press conference had made it seem. There were disagreements. Methodologies were called into question. There was genuine debate. It was science, and finally all my students were seeing it live in action.
Would I repeat this experience? Certainly, if a good opportunity arose. The circumstances may have been unique but I’ve bookmarked NASA’s news feed just in case.
Mike Reid is an assistant professor in the Department of Astronomy and Astrophysics.