Discovery Chemistry: Balancing Creativity and Structure Mauri A. Dizler and Robert W. Ricci College of the Holy Cross, Worcester, MA01610
There is widespread interest in find in^ ways to emphasize the process of investigation in the i'trod;cior) chcmi s t cumculum. ~ While there is no uueshon thnt students must continue to learn the fundamekd theories of the discipline and acquire skills in solving related problems, there is a growing appreciation for the value of having students create their own knowledge through a discovery based pedagogy. It is argued that by emphasizing investigative activities in introductory courses we more accurately reflect a way of knowing that characterizes our dynamic discipline (1-9). In 1991 we reported in this Journul that we had implemented a general chemistrv curriculum driven bv a series of process-oriented, laboratory-based discovery exercises (3).We have continued to refine this "Discovery Chemistry" cumculum, drawing guidance from our original premise that chemistry should be learned in much the same way that chemistry is practiced. Students actively participate in the scientific process as they are guided to rediscover many of the fundamental concepts of chemistry. Instruction in the process of chemistry then serves as a means of introducing the content of chemistry. Consequently, the laboratory experience is given a preeminent role; new information is discovered in the laboratory and then used as the basis of further lectures and discussions. The cooperative nature of the scientific enterprise is simulated by relying on division of the labor, pooling of data, and group discussions of laboratory results. In our previous report we described several examples of student exercises that supported the contention that a general chemistry course could be built around student-generated discoveries. We are now in our fourth full year (six to nine sections per year) of teaching general chemistry to majors and non majors with the Discovery format. Eight different faculty have participated. Our 20 General Chemistry Discovery exercises designed to introduce basic concepts have been through a series of iterations and refinements. A variety of models have been or are being developed for inquiry-based courses. Some, like ours, focus on the rediscovery of fundamental principles. Others draw on current applications of chemistry to stimulate student interest. For instance, at the University of Michigan some laboratory assignments are based upon investigations of current problems in chemistry such as the creation of new painkilling drugs (7).Similarly, a t King's College (Ottawa, Canada) students use an open-ended investigative team approach to study projects that "relate to their experiencesof chemistry at work, in the world around them, or to specific areas that are of interest to them" (8).While these programs differ from ours in that the questions asked are more applied in nature, they share our emphasis on chemistry as an investigative laboratory science. Regardless of the exact nature of the program, we note that finding the proper balance between a structured laboratory environment and opportunities for student creativity is a common concern among faculty using inquiry-based teaching.
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'Current address: Millikin University, Decatur, IL62522.
Creativity Versus S t ~ c t u r eAn : Ever-Present Challenge
Most traditional introductory laboratory exercises are highly structured and lead the students through a predictable series of events. These exercises are seen as making efficient use of limited laboratory personnel, space, and student time. They emphasize the importance of a structured and orderly process of making and recording observations. Also, they can be used effectively to introduce important manipulative skills. On the other hand, the highly structured format can be criticized for favorine exoerimen& thnt verify rather than reveal chemical principles. Student creativitv is sacrificed because of its oerce~ved conflict with thestructured format. Thus, m k y traditional laboratory exercises, while useful, do not reflect the fundamental investigative activity that draws scientists to the laboratory. In contrast to the highly structured verification exerch cises. the com~letelvo~en-endedinvestieative a ~ ~ r o ato instkctional iabor&&yexercises is subject to criticism as sacrificingtoo much structure. In the extreme case. havine students&ve at new concepts through random or ; u structured experimental processes does not reflect the scientific process any better than overly structured verification exercises. The analogy from the popular literature that investigating nature by the scientific method is like methodically searching for buried treasure with a giant bulldozer (10)is a useful one. We do not train our students in the scientific method if we do not teach them the systematic, logical, and orderly processes that provide the foundation for creative insights. While there may be an element of creativitv and excitement in a com~letelvooenended experiment, &e find it preferable to usca st&ct$ed format to s u ~ ~ othe r t insights ex~ectedof the students in inquiry-ba~e'd'teachin~. The remainder of this essay is devoted to a discussion of the model that we have found to provide elements of both structure and creativity for laboratory sections as large as 2 5 3 0 students. 7.
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A Model for Successful Discovery Exercises
We have found that a three-part organization of the discovery exercise works well. Aprelaboratory discussion provides focus and structure to the exercise. Here we include a focal question; solicit hypotheses or predictions; discuss appropriate experiments; and consider the trends in data expected for each of the student hypotheses. The experimental section of the exercise is characterized by a division of the labor. Each student or small group of students is assigned a unique variation on the overall experimental theme. By pooling their experimental results students generate an extensive database from which they independently and cooperatively discern trends. The exercise concludes with a ~ostlaboratorvsession. Here. the interpretation of poolei data, either individually or'in groups, provides the student with the o ~ ~ o r t u n ito t vbe creative. ?hmughout the process the instructor remains a central figure, guiding and choreopphmg the activity, ensuring that student creativity is called for in small, manageable increments. Volume 71 Number 8 August 1994
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Prelaboratory Discussion-Structured Planning Askine the rieht auestion is an imuortant feature of a scienti& invesGgacon. Likewise, wl have found that a well-crafted focal question is central to a successfulDiscovery exercise. A good question will pique the students'interest, keep them involved in the progression of the exercise, and ultimately provide a sense of accomplishment when the answer is determined. The auestion should represent a logical bridge between a concept that the stud&ts already know and one that they are expected to learn. Early in the course, the students do not have a common base of chemical experiences. At this point, seemingly nonchemical questions can be the bases of exercises that both reflect the scientific process and introduce a series of chemical concepts. For example, the questions "What effectdoes aging have on the mass of a penny?" or "What is the most efficient wav to uack baseballs in a carton?" effectivelv draw on thd stuients' common experiences and serve as the bases of very productive investigations. Furthermore, natural phenomena that are an integral part of the students' life experiences can be the focus of good Discovery exercises. For example, the question "Why is an aqueous solution of comer chloride blue while sodium chloride is colorless?"s& to work because of the students'inherent interest and experience with the concept of color. As the course progresses, the focal questions can draw on previous exercises that have become a part of the common experience. Althoueh a eood exercise mav intmduce a wide ranee of topics, inexperienced studenfs are uvenvhelmed irthe auestions do not initiallv focus their attention on a scecific i'ssue. Then, as the stuients gain experience with the investigative process, it is possible to replace narrowly fucused questions with an assigned task for a team of students. We find that this a ~ o r o a c hworks well in our exercise that introduces the equilibrium expression. Teams of students are assimed the task of finding a mathematical expression thacdesxibes the partitioning of a ketone between pentanol and water. In designing. the experiment, students will typically pose for themselves the question of whether the relative volume of the two phases is an important factor and whether the volume or identity of the ketone is relevant. As they begin preparing samples to investieate these relationshios. thev " mav " follow uu with more spegfic questions, such i s 'Does it matter in tvhich phase the ketone is initially dissolved?"Students enjoy the opportunity to express greater creativity when they design uortions of the exueriment. However. this is done within ihe framework they have learned in the previous exercises and subject to oversight to ensure that a systematic approach is used. While the instructor generally formulates the questions a t the prelaboratory meeting, students are responsible for generating hypotheses and predictions. We find that this activity is best carried out as a group exercise. Although not all students will offer a hvuothesis. thev are all required to endorse one as the most reasonible."Adiscussion of the basis for proposing or supporting a hypothesis forces students to consider how they have extrapolated from the known to the unknown. Debate between several confliding hypotheses heightens student interest in subsequent exuerimental work as thev consider the t-. w e of evidence t h k might support their arguments. Moving from the student hypotheses to the experimental work is one of the meatest challenges faced bv the instrucof saety and effitor. It is our pref&ence, for ciency, that experimental work be planned in advance by the instructor. We fmd that by carefully planning the timing and framework of the focal question the instructor can subtly point the student responses toward the planned ex-
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perimental work. For example, our stoichiometry experiment (3) is desiened to ~rovidedata to aetermine the shape &d slope k r a plotbf mass as a function of reactant mass for a series of related reactions. We ask the students how they could use small scale experiments to predict the number of tons of silver nitrate that must be ordered if their company is to produce 1000 tons of silver chloride (or silver bromide, silver oxalate, etc.). Since the question is framed differently than the stoichiometry problems thev worked in high school (differentunits, scale. and scenario), students rarely consider using traditional mathematical algorithms. By scheduling graphing -. . - theory, calibration curves, and extrapolation techniques during the previous lecture, the instructor can ensum that, cunsistent with the planned experiment, some form of the desired graphical extrapolation approach will be suggested. In some cases, perhaps because of an insightful and persuasive student, the class will quickly come to a consensus on the correct answer to the focal question. In these cases we ask one or more follow-up questions. For instance, in our exueriment to introduce the Beer-Lambert law we ask 'What'variables control the fraction oflight transmitted by a samole?" Since the students have used visible soectroscopy in a number of previous experiments, they easily proh concentration. and nature of the solute Dose ~ a t leneth. as important ?a&ors. To inject degree of uncertainty or curiositv with resued to the outcome. we follow UD bv asking them to predict the shape of a of transmiitance as a function of one or more of the variables thev have selected. &
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Data Acquisition-Shared Responsibility
As scientists we often find the gathering of data to be the most exciting aspect of an investigation as we watch evidence for or aeainst our hwotheses unfold before our eves. Since the Dikovery approach requires students to Eonsider the relationship between their hypotheses and the upcoming experimental work, they experience a sense of excitement that is often absent in traditional laboratorv exercises. The nature of a Discovery exercise requires more extensive experimental design than a typical verification exercise. Iia verification exercise students generally examine a specific system to verify or illustrate a general concept. In a Discovery exercise, the students must examine a series of specificsystems in order to discover the general concent. For exam~le.to discover that freezine ~ o i ndeorest s i k is dependent'on the number but not lidentity df the solute uarticles. the students must examine a series of different solutes, each over a range of concentrations. This need to examine a series of systems in a Discovery exercise highlights the central role of cooperation in a scientific investigation. Since an individual student will not be able to accumulate data on enough systems to discover a eeneral trend or urinciule. there must be a division of the laior and ultimat;ly a pbol&! of the data. For example, in our Beer-Lambert law exercise each student is eiven a unique pathlength cell or solute with which to st;dy the effect of dilution on transmittance. Consequently, the students must treat their classmates as coinvestigators rather than competitors if they are to discover the complete form of the Beer-Lambert law. While cooperative efforts are a necessar, component of most of our exercises they are also consisient 4 t h our overall goal to simulate the fundamental Drocesses of the discipline in our instructional strategies. Collaborative investigations and the sharing of experimental results are important aspects of the ch&nists'way of knowing. The sensebl'participstingoparticiating in and contributing to the overall scientific community is one ofthe most rewarding aspect softhe lifeofthe scientist. We
find that students appreciate an opportunity to experience this sense of belonging to a team and as a result find the laboratory exercise more fulfilling. We observe that the entire data gathering prccess often takes on a colleeial atmosphereUwithstcdents engaging in small group&scussions, elaborating on their hypotheses, and deliberating among themselves on the implications of their preliminary results. It has been our experience that group interaction is substantially increased by providing a discussion area (small tables and blackboards) adjacent to the student laboratory. Post-LaboratoryDiscussion--Student Discoveries
We find it preferable to have the students reconvene immediately after completion of their experimental work to pool and discuss their data. Occasionally, time constraints require that this discussion be postponed until the next meeting of a lecture section. Consequently, we find it important to link lecture and laboratory sections; all laboratory sections associated with a given lecture section are scheduled to meet between two consecutive meetings of the lecture class. Generallv the students' creative inskhts occur after a systematicevaluation of shared data. In most cases, the instructor plays an active role in this process. The instructor points out definitive experiments o r previously learned concepts that may have been overlooked, questions inconsistencies in student responses, and highlights insightful comments. The instructor might also suggest a graphical analvsis or the use of a thoueht exoeriment or model. Complex"questions are broken ldown'into a series of simpler steps, allowing the level of creativity or insight required to match the level of sophistication attained by the students. Ensuring that each student benefits from the group discoverv can be challeneine. Verv " few tooics from a tvoical intro&tary chemistry course are compietely new toevery student in the class. An appropriate question then, is "How can a group of students discover a concept if several members have orevious exoosure to the to~ic?"To olace this concern in proper perspective, it is important tdnote that for experienced scientists discoveries often reflect a new insight into already familiar topics. This view of a discovery has been illustrated by attributing the discovery of the earth to Galileo when he first viewed his familiar surroundings as an orbiting planet (11).An extension of this view of discovery to student-scientists is apparent in our exercise for the mole concept (3).Most of our students have used the mole concept extensively in their high school chemistry courses, yet they still experience the excitement of a new insieht when thev discover what thev refer to as " *factoring out differences in unit masamas an approach to eeneralicine stnichiometric rclationshios. Thcv do not inkally relac this concept to the "conve~ionto"molesxstep with which thev are all familiar. The students discover the familiar mole concept by seeing it in a new light during the Discovery exercise. Interestinelv. we have not found that students oreemot the discovery by discussing the results of ihe exircise with former students or by consulting their textbook in advance. Several issues are relevant here. In general the goal of our exercises is the discovery of a fundamental concept rather than a single fad. Most instructors of general chemistrv can attest to the fact that students rarelv can be persucded to pick up fundamental concepts from casual conversation with a roommate or an unassigned reading of the text. Further, since students offer mukple hvpotheses, a student with the correct answer prior to the exercise is generally no more persuasive than those offering incorrect hypotheses.
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Even though discoveries are made as a group, many students can experience the fulfillment of personally contributing to the final discovery Experiments can be designed to produce data that will lead to the discovery of a series of related concepts or lead to a series of insights of increasing difficulty on a single concept. For our exercise that introduces the equilibrium coktant, teams of students try to determine the mathematical description of how a ketone partitions between pentanol and water. Within each team there will be a student that notes the constancy ofthe concentration ratio of their particular ketone between organic and aqueous phases. When the teams gather to compare results. another student will see the trend involvine the magn&de ofthe partitioning constant and the alkyl ihain length (or molecular weight) of the ketone. Still another student will relate this trend to solubility factors. All of these students can be credited with making a laboratorybased discovery, although at different levels of sophistication. Freauentlv an exercise that leads to a single discoverv requires a siries of insights. Just as many students contribute to the overall data pool, a number of students will contribute an insight that advances the group discovery. Our exercise to discover the Nernst equation illustrates this orinciole. Pairs of students are eiven an electrode svstem t o in;estigate. They are assignYed the task of fmd& the relationshio between cell ~otentialand concentration of one or more ilectroactive spkies. Each pair will discover a form of the Nernst equation for their specific electrode. Because of the arbitrary nature of whether students use natural or base ten logarithms and whether they look a t the ratio of oxidized to reduced species or the inverse and becuase of the inherent differences in the number of electmns transfined in the w~ctions,theindindual equations will appear to be drarnaticallv different. Even pairs of students-who examine duplicate systems will very likely find different forms of the Nemst equation. Given sufficient time and appropriate guidance, the students can work together to come up with a single general form for the N e m t equation. Since this requires the decision to uniformly adopt either the natural or base 10log, a selection of a uniform convention for the form of the lop term. a decision as to how to account for differences resilting from different numbers of electrons. etc. manv students contribute to the final form of the equation. E H C ~student experiences a sense of pride in the equation that they helped to "discover". Perhaps even more importantly, all students see in a new light the many general equations that they are called on to learn during the course. Role of the Instructor
The active role of the instructor throughout the exercise highlights the differences between our structured model for inquiry-based learning and open ended approaches. Our experience suggests that by retaining control over the direction of the experiment the instructor can better demonstrate selected processes of discovery and still offer significant opportunities for creativity at various points in the exercise. The techniques for making discoveries are second nature to us as scientists. However, unlike the content of our discipline, these processes are not something that we oRen verbalize. After four years of teaching Discovery Chemistry we are just beginning to sense the beauty and complexity of the thought processes that are an integral part of the scientists' way of knowing. It takes all of our pedagogical skills to discover, on a daily basis, the right mix of interaction and passive observation that balances the need to present the chemists'elegant way of thinking with the importance of fostering student creativity. Volume 71 Number 8 August 1994
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Students wntinue to surprise us with their unusual and often creative hypotheses and interpretations of experimental data. The instructor must fmd ways to accommodate this unexpected input within the structure imposed by other pedagogical goals and the restrictions imposed by time and facilities. We find that our interactive Discovery format requires the instructor to exercise as much creativity as he or she is expecting of the students. Each of the eight individuals that have used the Discovery format in the general chemistry courses at Holy Cross have adjusted the balance of wntrol to suit their personalities. Some allow considerable student input into the direction of the Discovery exercise and subsequent lecture classes. Although these instructors are active participants, they exert subtle control only to keep the exercise in line with the planned experimental set-up and the need to cover basic conce~ts.Other instructors refer to redirect the students out; more traditional paths through the ex~erimentand subseauent data interoretations. Reeardless bf these individual kodifications, n&ly all who hive participated have found the overall format to be invigorating and professionally fulfilling. Although responses are variable, many of the 900 students who have been through our Discovery courses report the laboratory exercises to be exciting and rewarding. The creative aspects of the exercises
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preclude the horedom of simply following a recipe. The structure imposed hy the master scientist minimizes the fruxtration of an overwhelming task. Perhaps most importantly, chemistry is presented as an ongoing investigatwe orocess rather than a static collection ol'factx and numerical problem solving algorithms Acknowledgment Discovery Chemistry at Holy Cross is a truly collaborative effort involving all the chemistry faculty and staff. One of the authors (M. Ditzler) would like to acknowledge the support of the PEW Charitable Trust. Support from the W. M. Keck Foundation, The Kresge Foundation and the National Science Foundation( DUE 9254016 ) is also gratefully acknowledged. Lierature Cited 1. Allen, J. B.: Barker, L N.; Ramsden. J. H. J Chem. Educ. 1%8,61,5333-34 2. Wojeik, J. E J. C k m . Edue. 1990,67,587488. 3. Rieei, R. W.; Ditzler, M A. J. Chrm Educ. 1991,68,226231. 4. Enui",D. K.J.Ckm.Educ. 1991,m, 862. 5. Riekard,L.H. J.Ckm.Educ. 199% 69, 175-177.
D.J C k m Educ. lsBS,7O,7679. 9. Pmi, L 0.J. Chem.Edue. 1893,7O,145-146. 10. Pimig, R. M. Tan end t h a M o/Moloreyele Moulfonanae, Morrow,:New York, 1914. 11. &ight, D., Ideas in Ckemistni, Rutgers: New Brunsuiek, NJ, 1992;p. 4. 8. M a h a P G.: N e w a n , K E.: Bestman, H.
