Franklin & Marshall College

Each of us faces the ultimate question that has bothered humans since the beginning of awareness. Great minds like Plato, Beethoven, and Hemingway have tried to give their personal answers, but it continues to perplex every one of us. The ultimate question is simply, "What are we?" Astronomy gives us an important part of the answer, and that makes introductory astronomy the perfect science course for undergraduates.

Certainly part of the answer goes beyond the physical universe. We define ourselves by what we create, what we worship, what we admire, what we demand of each other. But a major part of the answer is imbedded in the physical universe, and for this we turn to astronomy. No other science speaks so clearly about our place in nature. We cannot hope to understand what we are until we understand where we are in a universe filled with worlds, stars, and galaxies.

The introductory astronomy course is the ideal science course to help students understand what they are, not because astronomy is a better science, but because astronomy is different. There are only about 10,000 astronomers in the world, not enough of a crowd to fill a football stadium. So our goal is not to attract large numbers of students to our profession. Also, the principles of astronomy are not needed for any particular career, as is the case for chemistry, for example. That means we don't have to teach the basics of astronomy to future physicians, engineers, lawyers, or business leaders. When we walk into our introductory astronomy classrooms, we champion goals quit different from teachers of other sciences.

Goals

We who teach introductory astronomy express our goals in different ways, but the words all boil down to two things. First, we want our students to understand where they are in the cosmos. The universe is elegant and beautiful and we want our students to enjoy it and admire it as we do, but more important we want our students to understand astronomically where they are. Not only where they are located, but where they are in the evolutionary processes that have shaped the universe. Only then can they begin to understand what they are.

Our second goal is required by our first goal. It is not enough to tell our students what we know. We must also tell our students how humanity has learned to understand the physical universe. That is, we want them to understand science as a way of learning and knowing about nature. Not only must they understand the methods of science before they can accept the validity of scientific knowledge, but they must understand the nature of science if they are to function in the 21st century.

One talented teacher at a small California College summarizes these two goals in a slightly different way: "By the end of my course, I want my students to know a few basic things: that they live in a very big universe that is described by a small set of rules; that those rules are knowable; that the human race has found a way to figure out the rules."

The most important concept in our introductory astronomy courses is the process by which we learn about nature. That process is science. The old three-step scientific method -- observe, hypothesize, experiment -- was never a good description of the scientific process. It makes science sound like a sausage grinder that stuffs facts into theories. The real process of science is much more complex, more human, more creative, and more exciting.

Some of our students see astronomy as the dreary application of a few laws of physics to the study of the sky. In fact, astronomy is tremendously exciting because those laws of physics are tools with which we can discover the secrets of the stars. The central concepts of astronomy show how physical laws prescribe natural processes. Thus we see how Newtonian gravitation prescribes orbital motion, how nuclear fusion prescribes stellar structure, how the physics of condensation from a vapor prescribes planetary compositions. Our goal is not for our students to learn the physics, but to understand how the physics prescribes the universe. In learning these concepts, our students will see physics, not as a set of laws to be memorized, but as a set of powerful tools that help us understand the universe.

Implementation

I began teaching introductory astronomy in 1970 with a list of 8 class goals and 7 laboratory goals. Over the years I have focused more clearly on serving my students needs rather than my own expectations. My goals have now merged into the two discussed above. I want my students to begin to understand two things

• What we are
• How we know

Like any good tool, a course must be carefully sharpened. I have gradually modified my course to focus on helping students understand themselves and the role of science.

To this end, I have made the interplay of evidence and hypothesis the principal organizing theme for my course. Basic observational facts are introduced, hypotheses are synthesized, and further observations are discussed as evidence supporting or contradicting the hypotheses. For example, the origin of the solar system, is discussed in this way. The students begin by surveying the solar system to compile a list of its principle characteristics. Then they see how the solar nebula hypothesis springs logically from those characteristics, and finally, they see how additional discoveries help us understand, test, and elaborate the theory. We discuss the origin of the solar system before we discuss individual planets in detail, and that gives the students the theoretical background to use the information about the planets as further tests of the theory.

Over the years, I have decided that postponing the discussion of the solar system until after stars and galaxies is a further aid to the students. If we discuss the solar system first, the students have no background to understand what the sun is or how it formed. They don't know how the chemical elements were made or how common stars and galaxies are. They have no perspective from which to evaluate the solar system. It is better to discuss stars, galaxies, and cosmology first, and then fit the solar system into the students' understanding of the universe as a whole.

On the other hand, teaching techniqes and the order of topics is much less important than the goals we set for our courses. We may teach in the traditional order, we may teach in a cooperative mode, we may teach via television or computer networks, but if our goal is to teach facts, we fail to serve our students. I run my classroom day by day in whatever way works best for the students I have, but my goals do not change. I want my students to understand themselves as part of the universe. Everything should focus on that.

Most of all, I want to encourage my students to momentarily step aside and observe how they are thinking instead of concentrating on what they are thinking. I want them to understand the method we call science as a natural human approach to solving problems, and that means I must sometimes turn the discussion away from the facts of astronomy and toward the philosophy of science. What is the difference between a hypothesis, a theory and a natural law? What do we mean by certainty in science? How can we use statistical evidence? Why do scientists see to be so skeptical of every new idea? For beginning college students, what they learn about science may be more important to their lives than what they learn about astronomy.

How many of our students feel uncomfortable with mathematics? Too often we isolate the math from the main story of our courses as if the math was a bowl of anchovies that could be added to taste. I want my students to understand what science is, and that means they must see that mathematics is an indispensable part of science. At the same time, I want my students who are less comfortable with math to be able to follow the arguments. To serve these students well, I include necessary math in my class without apology, to assure the students that the mathematical aspect of science is not peripheral but is an integral part of our understanding of the universe. At the same time, I avoid arguments that depend entirely on mathematical reasoning, and thus a less mathematical student can follow the story. My experience over the years is that students are more mathematically capable than we expect, more capable than they will admit, and more capable than even they suppose.

Remembering and Understanding

Our task in teaching astronomy is not to teach facts to be remembered, but to teach relationships to be understood. That is, we must be concept-oriented instead of fact-oriented. It is easy to teach facts, easy to test facts on exams, and students feel safe memorizing facts and recalling them when needed. But our two goals require that we go beyond facts. For example, a teacher might state that Jupiter is the most massive planet. It would be easy to test that fact on an exam, and students would feel comfortable memorizing that fact. But the real insight lies in the process that made Jupiter massive. Until we understand the concept of the solar nebula hypothesis and the processes by which the inner and outer planets grew, the large mass of Jupiter is just an isolated fact. Once we understand the concept, the mass of Jupiter fits into a bigger picture. It not only makes sense, but it is easy to remember without memorization. Understanding is always a more robust form of learning than memorization.

In my course, I have avoided introducing facts unless they are needed to explain astronomical phenomena. Moreover, I have focused discussions to show students how astronomers use facts as clues to new hypotheses and as evidence to test existing hypotheses. Of course, we need facts as grist for the mill of scientific inquiry, but we should not make the facts an end unto themselves. Our goal is understanding nature rather than remembering facts.

There are no Oscars for college courses, but teachers of introductory astronomy can take heart that they would be big winners if there were. Introductory astronomy focuses on the things that non-science students should understand to function in the modern world and to appreciate their lives in this beautiful universe. That is why introductory astronomy is the perfect science course. It focuses not on the facts of astronomy, but on an understanding of what we are, and how we know.