What to do in a big lecture class, besides lecture

Dr. Douglas Duncan

University of Chicago & American Astronomical Society
Education Office

Educational studies have clearly shown that for significant and lasting learning to take place, students' minds must be active. When students take a new concept and begin to relate it to what they already know about the world, try to apply it to solve a problem, or explain it to another person, they are engaging in the sorts of activities--active learning--that have been shown to result in lasting understanding. Listening passively to a lecture, even a good, clear one, fails to achieve the same results. When taught by traditional means, students can often pass a test, yet be unable to apply the same concepts in the real world. Furthermore, much of any knowledge they have gained passes from their minds not long after the final exam. This article describes one method for encouraging active student learning in a "breadth requirement" course for non-science majors. This method has also had a considerable positive influence on students' attitudes about science.

"Challenging" Students

Many teachers are disappointed when students cannot apply concepts the teacher thought students had learned in situations different from those covered in class or in the real world. Teachers who notice this and are disappointed are probably a minority. Research suggests that a majority of teachers overestimate what their students have learned. Students overestimate their own learning as well. The videotape, "A Private Universe" (available from the ASP and highly recommended) demonstrates this in a dramatic (and entertaining) way. One can be a good clear teacher, appreciated by the students; one can even win teaching awards, and yet there may be less lasting learning taking place than the teacher and students think. Such findings present a clear challenge to those of us who teach science.

In educational jargon, constructivist learning means that a student has learned a concept in such a way as to build it into his or her own world view; the student must actively work for this to occur. Constructivist methodologies are built into the National Science Education Standards, which emphasize that science is something students must do, not just memorize. This has been done because active learning has been shown to be more lasting. Jargon aside, many readers (scientists and nonscientists as well) may recognize the truth of what I've described by thinking carefully about their own experiences. When Richard Feynman lectured my freshman physics class, his explanations were wonderfully clear and simple. Only when I went to do the homework problems did I realize that there was much more to the material than I first thought. And only after many hours of work did I actually begin to understand many of the concepts in a thorough way.

A related conclusion from this sort of research shows that when students have a wrong idea, learning a correct explanation often will not change their minds in a lasting way! Contrary to what is sometimes assumed, students don't enter their first science class without ideas about science or how the world works. At an early age our thoughts are influenced by watching cartoon characters run off cliffs, hearing explanations from others which may or may not be accurate, etc. Aristotle held concepts which are sensible but wrong. So do our students, and these are surprisingly resistant to change. The challenge that research shows is the evidence that we must allow our students a chance to apply their own ideas in new situations, and that only if these fail are they likely to replace previous concepts with ones learned from us.

Luckily we know the techniques (or methods) and circumstances that best facilitate active student learning. The methods typically take more time, and they are most effectively done in small groups. These methods include hands-on activities, connections to the real (outside the classroom) world, and discussion of results. Those of us who teach at colleges and universities, however, almost always teaching large lecture classes. Conditions in those classes are diametrically opposed to those which enhance true learning. What can one do, then, in a big lecture class to enhance the active kind of learning which has been shown to be desirable? In other words, "What can one do in a big lecture class, besides lecture?"

At the University of Chicago I have been experimenting with some simple techniques which are easy to do, and which have shown considerable success. I teach the breadth requirement course which includes only first-year, non-science majors--about 100. The class meets twice a week, for an hour and a half, each Tuesday and Thursday. There is an associated lab and recitation which meets once a week. One and one half hours is a bad length for a lecture. Even when the teacher is lively and clear, student attention tends to wander, and learning diminishes, well before 1 1/2 hours pass. This extensive class length gave further incentive to try something besides a pure lecture.

Before discussing my method, which I call the "Weekly Challenge," I need to outline the goals of the course. Success can only be measured when there is a standard to measure it against; my goals are given in Box 1. A powerful start to improving science teaching is to actually write down your goals and discuss them with your teaching assistants (T.A.s) and students before beginning to teach. As obvious as this sounds, it is rarely done. When it comes to Astronomy 101, many astronomers "Just do it." I found that examining the actual class goals gave me the freedom--indeed, the imperative--to discard what wasn't supporting the goals and to try some new ideas that might. I discuss these goals with the T.A.s, and with  students, the first day of class.


Primary Course Goals:

  1. Encourage a sense of awe and an appreciation of the topics investigated in modern astrophysics. (Such as the origin of the universe, the formation and evolution of the sun and the earth, the nature of space and time, and the search for other planets and life in the universe.) 

    • Develop a sense that some topics in astrophysics are so interesting that a student will want to follow them on his or her own (i.e. affect the students' attitudes about science). 

  3. Facilitate student understanding of the scientific method and provide opportunities for their practice in its use. 

    • Develop critical thinking and reasoning skills--emphasis on the predicting/testing nature of science.  (This is very useful outside of the science class!) 

  5. Provide opportunities for teaching assistants and myself to improve our  teaching skills. 

Secondary Course Goals:

  1. Provide students with a moderately comprehensive introduction to the topics and results of modern astrophysics (enough information that they can put into context discoveries they might hear about, or read about, later). 

  3. Provide students with opportunities to learn, and use, quantitative reasoning skills. 

Box 1

A goal worth discussing in more detail is that of getting students to understand what science actually is. What distinguishes science from other forms of learning is its emphasis on predicting and testing (experimenting) as a way of sorting out ideas which sound good, but are false, from ones which present a more accurate model of how the world actually works. This is not what most of the students think upon entering my class. Working jointly with science educator Amy Southon, I have been anonymously surveying student attitudes at the beginning and end of the term. Our surveys reveal that a majority think of science as a body of knowledge--facts which they must learn. Furthermore, most students (as well as the rest of us, no doubt) think that most of their ideas are correct. They believe that if they write a good argument, they should get full or nearly full credit for their ideas. The notion that ideas must be constantly tested against external data is foreign to most of them. Suggestions that some of their basic ideas might be wrong is a surprise.

Multiple goals could therefore be addressed by a "Weekly Challenge." This is an experiment which is set up in class every Tuesday, 20 min. before the end of lecture. Students are told to form into small teams of 3-4 throughout the lecture hall. The experiment is not performed on Tuesday. At the beginning of class Thursday the predictions are collected, and then the experiment is done. Of course we choose experiments with counterintuitive results. This demonstrates the need to actually do experiments even when you think that you know the answer. Examples of the Challenges are given in Box 2.

  1. Subject: Visualizing large numbers; distinguishing between areas and volumes.  1000 marbles (purchased at a toy store) are put into 20 Styrofoam cups, 50 per cup. Next to this is a "dodge ball" (also from the toy store) almost exactly 10x the diameter of the marbles, with a small hole cut in it. For fun, we call them "Jupiter" and "earth." Students are asked, "How many marbles will fit into the large ball?" 

  3. Subject: Why astronomers build large telescopes.  A lens is set up to project an image on a screen. Students are asked what will happen if the lens is stopped down to 1/2 diameter. 

  5. Subject: Refraction.  Students are asked if glasses would work in a swimming pool. Or (a more dramatic and feasible alternative) they are told that the index of refraction of Pyrex and Wesson oil are the same, and asked what would happen if a Pyrex stirring rod is immersed in oil. 

  7. Subject: Motions of the sky.  Students are asked what would the motions of the sun and stars look like during the course of a year from the N. Pole. (What happens every day, and what happens during the year? What would you see?). This is good if students can be taken to a planetarium to demonstrate the answer. 

  9. Subject: Light and color (transmitted).  A slide project has a slit put in it instead of a slide, and the beam is projected through a prism to create a nice, bright spectrum on a wall. Students are asked what will happen if a red filter is put into the beam of white light before the prism, or into the dispersed beam after it (they often give two different answers). Students could later be asked, "Where does the red light go? How could you test what you just said? 

  11. Subject: Light and color (reflected).  The same spectrum as in #5 is used. Students are asked, "What will happen if a red apple is moved through the spectrum. A green one?" 

  13. Subject: Gravity and acceleration.  During the week when dynamics and the law of gravity are taught: A bowling ball and a small steel marble are passed through the class, so that each student has a chance to hold them. I tell students that I will drop both, and that by combining two equations they have learned they can predict how the acceleration of the large and small masses will compare. A large ladder is procured and the balls are dropped from the top. 

  15. Subject: Electromagnetic spectrum.  A 3 min. video taken by N. American Rockwell with a 10 micron infrared camera used day and night in a city and on country roads is shown. Students are asked with what wavelength they think the video was made. 

Box 2

As soon as the challenge is given, the dynamic of the class changes dramatically. Students not only pay attention, they invest great amounts of energy in discussion with their peers. Not only is this a chance for them to get more information, it is very important to students how they behave in front of their peer group; I was unprepared for the strength of this response. Students quickly forgot all about me, and began to argue their ideas quite passionately with each other. It was not uncommon for groups to stay beyond the end of the period, lost in discussion and argument. On the week when the challenge was the Galilean one of dropping a heavy and light object (#7 in Sample "Weekly Challenges"), students were reported on Wednesday dropping various objects off dormitory balconies and timing their fall. Tennis balls stuffed with items to vary their mass were apparently the favorites. The key promoters of this high level of class involvement seem to be a good choice of "Challenges" based on simple, concrete experiments, and the division into small groups. Naming the experiments Challenges was a fortunate accident. Students often took the name literally--as an enjoyable challenge to them. The interest generated by the challenges, and the fact that they were graded, likely contributed to the high class attendance this course enjoyed.

Surveys taken at the end of the term revealed very positive student responses to the Challenges. When asked to rate on a 1-4 scale how useful they thought various aspects of the class were in helping them learn (1= not useful; 4= very useful), students gave the Challenges an average rating of 3.0. When asked how enjoyable various class aspects were, they gave the Challenges an average rating of 3.1 (where 4= very enjoyable). When initially asked, only 15% of my students said that they liked science.  When asked at the end of the term whether the class had changed their view of science, a remarkable 88% said yes. Following are some typical student comments suggest it just might:

And my personal favorite:

Since one of my goals is to positively affect student attitudes about science, most surprising to me when we began to survey student attitudes at the start of the term was the large number who described science not as difficult, but as boring. Showing that Challenges can address affective goals as well as help students understand course content, many students remarked on the final survey that they discovered science could be interesting, and creative. Since most scientists I know particularly enjoy the interest and creativity science holds, it seems a great shame that students reach college thinking just the opposite! That this course approach altered the view of science of so many of the students convinces me that it is a good one which should be tried more widely.

[Any materials mentioned in this article are available in their entirety from the author .]