The following draws from Dr. Shahn's paper Foundations of science: A lab course for science majors, published in D.E. Herget (Ed.), More history and philosophy of science in science teaching, Proceedings of the first international conference (pp. 311-352). Tallahassee, FL: Florida State University.
(....) Learning requires the student's engagement in four activities, all intended to result in thinking: reading, listening, doing, and writing.
Reading, Lectures, and Listening
We have had great difficulty locating appropriate reading material. Our attempts at finding "selections" have often resulted in far too many pages, still leaving far too many gaps in what we consider appropriate coverage. With this as starters, it is not surprising that students often find the reading assignments obscure. At the same time, many of our students have been unable to read "variations on a theme", that is, two different approaches to the same material, each presenting a slightly different emphasis. An alternative, preparing our own text, has been tried by Professor Bennick (Physics) who has had major responsibility for developing the first story line. Student response to his material is very positive. The goal and achievement of his endeavor has been the frequent presentation of major advances in remarkably comprehensible form. For example, while most of us identify the significant achievement of Copernicus as the removal of the center of the planetary system from the earth to the sun, few of us are aware that this simple device permitted the determination of the relative size and order of the planetary orbits. The actual calculation requires only simple geometry, but it is not included in most texts on this subject. With other calculations of this sort the role of geometry in understanding the heavens is illustrated as well as the unifying role of what we call the Copernican revolution.
Listening occurs in the lecture hall. In fact we hope that this results in understanding. Unfortunately, many students, and probably a majority of freshmen, don't know how to "listen with a pencil". In our first year we had several lecturers, with as many different styles of lecturing. We rediscovered that students will write down what is written for them on a board or screen, but that they are at a loss to abstract as they listen. We had lectures that were filled with relevant illustrative slides that students couldn't summarize. And we had lectures punctuated with appropriate demonstrations. The latter were well received, but not immediately understood. They were viewed more as the magic which may have been their ancestors than as phenomena which are related to each other by the logic of scientific understanding. Professor Lavallee (Chemistry) has exploited a number of these to make points, often explosively. Only at Professor Duschl's (Curriculum and Teaching) urging did we finally realize that students needed at least lists of names of these, and better yet brief summaries of their conclusions. The point of this is that serious consideration has to be given to ways in which the students can be made active participants in the learning process, even as the presentation of material is more or less traditional. Just as the story lines of the course are thought of as skeletons to which the content is attached, so the lectures must be seen as only part of an "information delivery system" which includes the activities of laboratory experiences and writing as well. In these latter, of course, the student can in no possible way be passive, but must become an active agent in his own learning.
Observing and Doing
One major conclusion that has found its way into the modern scientific world view is that there is an outside world susceptible to objective observation, in sense that "yours" are as good as "mine". However, not all observations can easily be described in words, or even in pictures. Before we can master the language that refers to the world, we have to become familiar with the "things" that the language refers to. Some of these things are phenomena, or events that recur under standard or controlled conditions. Others are processes, or ways in which they occur. And still others are real "things" such as rocks and bones and flowers and mysterious white powders. The development of science follows the study of these various phenomena, processes, and things, and the place where these are studied is the laboratory. The study itself involves the act of doing.
The goals of this course would be ill-served were we simply to follow cookbook procedures. Rather, we view the lab as an opportunity to come face-to-face with part of the real world. The labs are implicitly based on what has been called a "learning cycle" approach. In this, the student explores, analyses, and applies. In short, the labs are the places where students find out what the substances and problems are that have confronted scientists, and have become the bases of science. In the first instance this approach enables the student to identify what is to be studied further in the sense that "that, there" can be specified even before it is named. Next, after naming it, "that, there" can be studied to find out what can reasonably be inferred from it, what it is, how it is held together, how its workings can be described, and, if possible, how they can be explained. These are the activities of scientists, this is the process of science, and by providing the opportunity for doing we are better able to convey--more fully than we could if we were limited to words--what the nature of science is.
As we worked on the labs, our skeptical colleagues frequently asked "What would be done in a lab for nonmajors that would be better than what was usually done?" These are some of the answers: a full detailed discussion of the lab exercises and their relationship to the goals of the course and our view of the students' learning process is presented in Appendix II.
We have given students lenses to play with, and with minimal direction at the end of three hours they had constructed telescopes. We started a lab on indirect measurement--critical for understanding the way in which a scale was placed on the heavens--with paper triangles so that we could be sure that students really knew what similar triangles were, and what properties they had; by the end of the lab the students were determining distances across the street. We repeated Galileo's experiments with rolling balls and, true to our self-imposed restrictions, we insisted that we use the time measuring technology available to him as well. This meant weighing water, the technique of the water clock. His reported accuracy -- "one tenth of a pulse beat" -- was reproducible, and more than adequate for reasonable quantitative results in a late twentieth century laboratory. (In fact, the limitations on accuracy are due to human physiological reaction time, not technology.) In this way we not only do science, but we show that while progress may in many instances be limited by technology, in many others it is the lack of a concept that is limiting. The Greeks had the technology to discover Galileo's laws of motion, they lacked the freedom of the mind.
To reinforce the concepts that Galileo's experiments were so instrumental in establishing, we go on to repeat the experiment with 20th century technology. In this case we use an air track coupled with a sparking device. The air track suspends a glider on a cushion of air so that it is essentially frictionless, and the spark provides a time measure accurate to hundredths of a second. The results are of course much the same as those Galileo (and we) obtained with a rolling ball, but the students are shown that there is more than one way to skin a cat. At the same time they are prepared to use the modern instrument to study Newton's second law and the conservation of energy. We also use these labs to demonstrate projectile motion on an air table which provides a frictionless plane on which a puck can slide. This, too, is conceptually similar to an apparatus described by Galileo, but rather than use approximate measurements of position we videotape the trajectory of a projectile and use a frame-by-frame analysis to show that horizontal motion is uniform, while vertical motion independent and is uniformly accelerated.
In other labs, as we modified what was traditionally done by freshman to make concepts more apparent, we have developed approaches that will find their way back into the major's courses. This was particularly the case where the liberation of "fixed air" (carbon dioxide) from sodium bicarbonate (baking soda) by mild acetic acid (vinegar) was studied. The traditional approach has been to use an "indicator" (such as litmus) which changes color to tell when a reaction had reached completion. The mechanism of such an approach is extremely hard to get across to beginning students, and questionably worth the time and effort if it is not likely to be exploited in future labs. Our solution was to use the equally time-honored approach of letting the reaction go to completion by adding vinegar until no more gas is liberated. This particular lab is in the midst of a sequence which starts with a simple exploration of the relationship between the volume and "pressure" of the gas contained in a stoppered syringe, and goes on to experiments in which it is shown that the relative "particle weights" of magnesium and calcium are 25 and 40, in excellent agreement with currently accepted values for atomic weights. The fact that students find these numbers emerging from their own work, goes a long way towards making the abstractions of the invisible world real to them. We attribute a major part of our success to the process of developing groups of laboratory exercises in which related concepts are developed sequentially, but in digestible portions. We feel that this, coupled with the historical approach which we follow in lab as well as lecture, is critical for the instruction of novice nonscience majors.
In the third part of the course we start the study of diversity by asking students to classify a variety of materials without the benefit of direction or a "key". This shows students the scope of the problem in two ways, by introducing them to the extent of diversity and to the very real problems that exist in trying to talk about this diversity. We have them mimic the process of selection to show that different phenotypes (colors of clips or bits of paper) can actually confer a selective advantage in different environments (patterned backgrounds). We discuss genetics as a mechanism for maintaining diversity, and use this as the occasion to explore the concepts of populations and statistics. We have also introduced a subtheme into this set of labs covering the idea that a particular kind of substance, DNA, is the material basis of genetic transmission. While it is possible to recreate the critical experiments in the course of one hectic lab session, it is clear to us that our students would retain relatively little. Our approach, then, as described above, is to break the story into a set of about half a dozen distinct concepts that will be presented sequentially in roughly 20 minute segments of labs. This extends the entire exercise over a period of several weeks, and at each stage provides time for the students to assimilate what has been done, and to see why more has to follow.
Having thrown out the cook book, our approach is to engage the students in the process of discovery by confronting them with raw materials, or with problems. Group discussions are used to encourage the class to propose and criticize their own approaches to answers. Since time is precious these discussions and subsequent activities are frequently guided by the instructors, but they are not lectures. "Wrong" approaches can often be quickly dispensed with by examining them in the light of class experience. The result is a mix of observation, talk, analysis, planning and action.
When possible, this leads to the collection of data. This becomes the occasion of yet another unusual feature of the labs of this course; they are the places where the numerical and mathematical aspects of the subject are met head-on. Thus students are introduced to data organization and analysis -- the techniques involved in tabulating, averaging, graphing and inferring algebraic form -- in the laboratory where the data are obtained. Since so many of our students needed remedial work before they entered this course we feel that this approach is the only fair one to follow. The mathematical skills which these students should now have are still only tools to be used under supervision in conjunction with the analysis of the scientific context in which they must be applied.
In sum, then, the laboratories are the places where the "objective" world of things, events and processes is encountered, explored, and to a limited extent mastered. The subjects of the labs are selected to complement the material that is covered in lecture and reading. The techniques of handling things (both the objects of study, and the tools used to study them) and analyzing data in the lab provide take-home lessons that cannot reasonably be expected to grow from more limited cerebral exposure.
Thinking and Writing
Yet another of the significant ways in which this course differs from other science courses is its emphasis on writing. This is because we strongly believe that a major part of appreciating the approach of science is the ability to "follow an argument", that is, to follow the reasoning processes that have led to some of the major advances of science. This skill will be crucial to understanding current and future advances as well. But this is not a skill that can be acquired simply by listening, or by reading; like other skills it must be practiced. In this course, the practice of finding numerical solutions for certain types of problems is pursued in the labs. Outside the labs the honing of critical thinking abilities is in the form of considering and writing answers to different types of questions.
In fact, we require several short papers, all in response to specific questions distributed during the term. As the course progresses these require the student to describe, explain, discuss, analyze, etc. specific points that have been covered in the reading assignments, lectures or labs, or to make comparisons between or among different approaches. The essay questions ask the students to write. As preparation for this there are more frequently distributed "focus questions" which direct the students to the sub-themes that run through all aspects of the course. The goals of both the essay and focus questions reflect a variety of ways of knowing. Thus we start by asking students to "describe" so that they become familiar with the problems of precision in observation and communication, but not burdened by the difficulties that may be inherent in "explaining" or "analyzing". This approach probably follows the individual's intellectual development as well as that of any of the sciences; one must be familiar with what one is studying before one embarks on a more abstract task.
Both focus questions and essays give us the opportunity to leave the linear approach that is required by any given text or set of lectures. In this sense we take the opportunity to explore such concepts as that of a "model" in science, or the notion of "schools of thought". The use of models is pervasive through all of science, although the use of the term may be relatively recent. The idea of schools of thought appears to be obvious, but in fact many of our students are not familiar with the fact that there may really exist contending approaches to -- or interpretations of -- a body of experience. It is often only in retrospect that these points can be made, and we do this with the focus questions.
The essence of this graded approach to understanding may be seen by the directive words that are used in our essay assignments. The first essay asks students to "state ... identify ... describe," the second requires them to "identify ... summarize ... present the reasoning," and the third says "discuss the contributions [of two of three men] relating them to each other." The fourth paper was a lab report which requires that the results of several labs be integrated, and the evidence accumulated (observations) be related to the conclusions. Since these labs accompanied several weeks of lecture and reading, we expected the understanding of all three areas to be integrated. Specifically, we are not looking for particular graphs or numbers.
The last essay in the first semester makes demands of students that reflect our expectations of appreciation of fact and broad comprehension of the synthetic processes of science. We start by naming four scientists who worked on the same problem. We then ask students to "A. Briefly characterize the approaches used by each and compare any two... B. Using four examples... show how [a particular] model could account for the observations. C. What [in your experience] is not adequately addressed by this model?"
A significant part of the course grade is based on these essays and written parts of exams. But we do not simply grade "answers". Instead, we return initial drafts with comments so that they may be revised and resubmitted for grades. (As an administrative aside, grading is performed by a selected group of graduate student lab instructors. They are generally instructed in the criteria to use, and we have weekly course meetings which cover lab preparation and general course management issues such as grading. We find no problems with this procedure, but it should be noted that these instructors are paid for the grading and course preparation in addition to their regular lab instruction wages. This is not a cheap means of teaching.) In practice we have noted that some students do not resubmit their essays, and others simply correct or modify their first drafts as indicated. Neither of these responses is what we planned, although the latter probably does have some effect. In many cases, however, we have noted significant improvement of revised essays compared to first drafts, as well as improvement in first drafts submitted at the end of the semester compared to those submitted at the beginning. These are both the effects we had hoped for, indicating that understanding can be achieved through the process of writing, and that the process of understanding can also apparently be effected by continued guided practice. (.....)