by Christa Colyer
Department of Chemistry
Wake Forest University, Winston-Salem, NC 27109
This case provides a brief, factual account of the pioneering work of Ignaz Semmelweis and his efforts to remedy the problem of childbed fever in mid-nineteenth century Europe. The case was designed to be used in a freshman seminar class entitled "Scientific Serendipity" as a concrete example of the "Scientific Method" in practice. It is important for students to understand that although there is no single sequence of events that must always transpire in order for scientific discoveries to be made, there is a set of commonly employed strategies to facilitate such discoveries. If we simply present a didactic list of steps in order to teach the scientific method, then we fail to allow students the freedom to explore alternative methods and pathways. Instead, this case elicits from students the key aspects of the scientific method in a discovery-based format, without resorting to memorization or rote learning. It is likely that the students may not even be aware that the study questions associated with this case are designed to guide them to conduct the scientific method through Semmelweis’ eyes. As such, this case is best used as an introduction to the scientific method, even before an explicit discussion of the method has taken place. Such a discussion could be subsequently held, and would be facilitated by referrals back to this case. This case could successfully be used in any introductory science course in which the scientific method is discussed and/or practiced.
The overall purpose of this case is to allow students to learn about the scientific method by "dissecting" the various steps involved in an important, historical medical breakthrough. More specifically, the objectives of this case are:
This is a short and effective case that requires only about 30 to 40 minutes to conduct in a freshman seminar class of 15 students. However, the use of this case should not be limited to small, discussion-based classes. It would be equally successful even in a large (60 or so student) introductory science class (for example, in a section of Freshman Chemistry), albeit an entire 50-minute class would likely be required to facilitate discussion among a greater number of students.
Progressive Disclosure Method
In order for students to figure out for themselves the important steps that constitute the so-called scientific method, this case should be presented by the method of progressive disclosure. That is, only one piece of information at a time should be distributed to the students, followed by discussion, before moving on to the next, more telling piece of information. If students are already familiar with the history of childbed fever, they will be tempted to jump ahead and suggest experiments that are not warranted by the observations presented in the earlier parts of the case.
Part I of the case, accompanied by its study questions, is distributed to the students. The students are then instructed to read the brief text provided and to consider the study questions before reconvening for a whole-class discussion. It has proven effective at this point to ask students to work in pairs with their nearest neighbor when considering the study questions. Not only will the pairs come up with more possible solutions to the questions than any given individual might, the pairs will also be more willing to relate their solutions back to the class as a whole. Be sure to emphasize that there are a range of possible answers to these questions – often science students are hesitant to write down an answer that is not absolute, and this hesitancy will severely stifle discussion. After a brief time, ask the class to come together again to share their answers to the study questions (see "Directing the Discussion: Expected Outcomes," below). Maintain a class list of the suggested explanatory stories and possible tests on one of the blackboards in the room (or on an overhead transparency), since the class will refer back to these lists after completing Part II of the case.
Next, distribute Part II of the case, with the same directions to students as for Part I: read the text and, in pairs, consider solutions for the accompanying study questions. After a brief time, the class will come together again to create a new list of possible explanatory stories and tests. These lists should be compared to the original lists, and explanations for any differences should be sought.
The case proceeds in this fashion of progressive disclosure, moving next to Part III and its study questions, and finally, Part IV and its study questions. The final question in Part IV, referring to the role of serendipity in this case, need not necessarily be addressed by an introductory science class that is focusing only on scientific method. However, even a class that isn’t intentionally going to discuss serendipity in science might well enjoy a brief exposure to it in this context, so that the instructor may be able to highlight serendipitous aspects of "regular" course material throughout the remainder of the semester.
Finally, the class should retrace their steps through this case in order to gain an appreciation for the "big picture." That is, an open-class discussion should follow after completion of parts I through IV of this case in order to encourage the students to recognize that they have just witnessed an example of the scientific method in action.
Directing the Discussion: Expected Outcomes
This case was specifically designed to elucidate the steps of the scientific method, defined as follows: (i) Observation, (ii) Statement of the Problem, (iii) Hypothesis, (iv) Experiment, [reiteration of (i) – (iv), as necessary], and (v) Conclusion. By establishing this set of events as a frame of reference, students are later able to compare future cases to these benchmarks and will come to appreciate the variability within this thing known as the "Scientific Method." It seems more instructive for students to deduce the "standard scientific method" from this case, rather than simply having them recite a list of five steps as defined by a text book or other source, since the latter tacitly implies invariability. Other instructors may, of course, choose to define the standard scientific method differently from the way in which it is defined here; for example, by citing experimentation as the first step, or by neglecting to include the statement of the problem as a distinct step. This case should be adaptable enough to teach other definitions of the scientific method, too.
In order to ensure that the class is able to ultimately conclude that their analysis of this case highlighted the pertinent steps of the scientific method, it is important to direct the discussion each time the student pairs return to the class as a whole. Below are some suggested responses that should be solicited from the students if they are not immediately offered by the students themselves.
PART I
Semmelweis’ initial observation, of course, involved the higher mortality rate for Division I births relative to Division II births. This first response constitutes step (i), "Observation," of the scientific method.
Students may identify several problems raised by the story in Part I. Some may question how to reduce mortality rates overall; others may question why there is a discrepancy between the mortality rate associated with the physician-attended births versus the midwife-attended births; still others may claim that the problem at hand requires understanding the mechanisms or causes of childbed fever. These responses constitute step (ii), "Statement of the Problem," of the scientific method. Be sure to point out that different people recognize different problems even when given the same observables. The ability to recognize a problem that is both important and solvable is an important skill for scientists to master.
When faced with the question, "What possible explanatory story might Semmelweis come up with?" students may suddenly become more hesitant to respond, since there is clearly no single answer here. To further complicate this part of the class discussion, the explanatory story offered by a student pair will likely only be applicable to the problem that they identified in the earlier question, and not necessarily to the problems identified by other student pairs. Thus, it is important to get each student pair to first identify the problem they considered and then to identify their possible explanation. You will already have created a list of possible "problems" from the discussion centered around the previous question, and so now you can simply create a parallel list of possible explanations. For example, a student pair might suggest that the problem is the difference in mortality rates between physician-attended births versus midwife-attended births, and that a possible explanation is that since midwives have only one primary task in the hospital, they are able to spend more time attending to their patients, thereby preventing deaths. Another explanation for the same problem might be the fact that since midwives are women, many of them might themselves have survived giving birth, and so they are more aware of successful survival strategies. By referring to your compiled list of explanations, be sure to point out to the students that each problem can have more than one possible explanation. Also, try to get students to offer the alternative and more commonly encountered name for an explanatory story, that being "Hypothesis." This exercise helps students gain an appreciation for the fact that a hypothesis is little more than an explanation for a problem that has been identified. Of course, in the strictest sense, a hypothesis must be "testable," but that idea can be raised during the discussion of the next question.
The final question of Part I asks for possible ways to test the explanations just offered. Undoubtedly there will be many different methods suggested to test each explanatory statement. Maintain a list of these methods (opposite the hypothesis to which they relate) as they are presented in the discussion. Again, point out that there is more than one way to test a hypothesis, and that sometimes many different experiments must be conducted before results can be properly interpreted.
PART II
After students read about the death of Semmelweis’ colleague and friend, they will quickly be able to revise their explanatory story. The revised version should include some mention of the implication of contamination from cadavers. Similarly, students will quickly be able to come up with new tests for their revised hypotheses. These tests may range from studying the consequences of intentional contamination of test animals to something nearer to Semmelweis’ own test, that is, prevention of contamination by handwashing. After compiling a list of revised explanatory stories and tests, be sure to refer back to the original class lists. Point out the importance of revision based upon new observation and experimentation. Try to get students to develop the idea that the scientific method is, in reality, an iterative process.
PART III
After reading about the outcomes of Semmelweis’ tests involving stringent handwashing policies, the students will easily be able to draw some logical conclusions, such as "handwashing prevents the spread of contamination from cadavers to birthing mothers," or "chlorinated lime water effectively prevents the spread of germs," or "childbed fever can be virtually eliminated by simple handwashing," and so on. Subsequently summarizing the suggested revisions to Semmelweis’ original hypothesis or experiments will again serve to illustrate the iterative nature of the scientific method.
PART IV
Students may be surprised to read about the dismissal of Semmelweis’ findings by the medical community. Although this aspect of the case does not have any real bearing on the elucidation of the scientific method, it does provide the opportunity to discuss some other interesting aspects of scientific research, such as scientific precedence, the dissemination of scientific information, scientific credibility, allocation of credit, and so on. It is suspected that Semmelweis had a difficult time convincing his Viennese counterparts of the importance of handwashing for several reasons. First, he was a Hungarian in Austria at the time of a xenophobic backlash in Europe, and so he was perhaps innately distrusted by his Austrian colleagues. More importantly, however, was the fact that doctors were reluctant to admit that they were, in many cases, the causative factor behind the deaths of their own patients. Additionally, the lack of indoor plumbing at the time made it difficult to obtain access to fresh water, and so the practice of handwashing would have been somewhat inconvenient regardless of its proven effectiveness.
Regarding the dissemination of scientific information, you may discuss possible reasons why Semmelweis didn’t publish his findings sooner. You may also discuss the development of the current methods of peer-reviewed scientific publication. Students may suggest alternative plans of action – perhaps Semmelweis could have enlisted the collaboration of a colleague at another institution to show the effectiveness of the procedures under someone else’s watchful eye, etc..
Finally, a discussion of the serendipity associated with this case could help to elucidate the role of serendipity in science in general. This, of course, would be most relevant in a freshman seminar course based on Serendipity, but it would certainly be of interest to other courses as well.