In the Laboratory
“Prompted” Inquiry-Based Learning in the Introductory Chemistry Laboratory William J. Green*† and Curtis Elliott Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458; *
[email protected] R. Hays Cummins School of Interdisciplinary Studies, Miami University, Oxford, OH 45056
Traditionally scripted laboratories are extremely effective in developing a student’s observational skills and manual dexterity and in conveying the importance of precision and accuracy in chemical measurement. Moreover, these laboratories provide an essential connection between theory and practice and allow for a deeper understanding of the often abstract concepts encountered in the first-year chemistry course. What the traditional laboratory often fails to capture, however, is the process of scientific inquiry—the excitement, intellectual challenge, and, indeed, the frustrations and rewards, that accompany scientific work. Whether fairly or unfairly, the introductory laboratory has sometimes been called a “cookbook” experience, and this culinary term has been used over many decades by generations of chemistry students. It is a description that is rarely offered as praise. Inquiry-based learning, by contrast, emphasizes the explicit use of the scientific method and invites students to generate and test their own hypotheses. In this approach, the student defines the problem to be investigated and the experimental or theoretical method to be employed. In some cases the project might evolve directly out of the course material; in others it might develop out of an antecedent experience, which, in some measure, has galvanized the student’s curiosity. In either case, the student establishes a kind of ownership, and, ideally, immerses himself or herself in the work, just as any serious scientist might. At its best, inquiry-based learning presents an opportunity for students to not only read about or imitate scientific investigation, but also to practice it. Importantly, it addresses one of the central concerns of liberal education, namely, the need to convey, as the historian Anne Sayre (1) has pointed out, the nature of scientific work. It is not surprising, then, that the inquiry approach has been adopted in a variety of settings throughout the undergraduate curriculum, including inorganic chemistry (for example, ref 2), organic chemistry (for example, ref 3), and introductory and analytical chemistry (4), and that some educators have argued that inquiry-based activities greatly enhance a laboratory’s pedagogical value (5). The inclusion of more active and engaged learning experiences in the chemistry curriculum is consistent with recent calls by the National Research Council (6) for greater emphasis on the construction and articulation of scientific knowledge and explanation. Our experience with both science and nonscience majors has shown that while students do tend to immerse themselves in inquiry-based projects with a degree of enthusiasm rarely generated by scripted laboratories, they often find it † Current address: School of Interdisciplinary Studies, Miami University, Oxford, OH 45056.
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difficult and time-consuming to propose an appropriate research question. The narrower the course topic—introductory chemistry as opposed to general science, for example—the greater the difficulty. The fact that interesting scientific problems rarely present themselves with the clarity of plums on a plum tree will come as no surprise to anyone who has struggled to find an acceptable dissertation topic. Hence the need for a “prompt”—or a list of projects that are conceptually and instrumentally appropriate—as a way of introducing inquiry-based laboratories within the strict time constraints of a semester-long course. Prompted Inquiry-Based Laboratories In the past two years, we have had an opportunity to teach the introductory chemistry course so as to incorporate both scripted laboratories and a prompted inquiry-based group project. The courses were taught at the Honors College of Florida Atlantic University (FAU) in the first two years of its operation, 1999–2001. Eight to ten scripted laboratories were selected from Laboratory Experiments (7), by Nelson and Kemp, the manual that accompanies Brown et al.’s Chemistry: The Central Science (8). Prompted inquiry-based laboratories (PIBLs) were chosen by student groups from a list provided by the instructors; five or more regular laboratory periods, plus additional sessions, as needed, were allocated for these projects. While we realize that there is a certain cost associated with the omission of scripted laboratories, we believe that the experience that students gain from carrying out an inquiry-based project—in which design and experimental problems, hypothesis modification, and uncertainty of outcome are all encountered just as they would be in any investigation—more than compensates for the loss of formal work. Some of the prompted laboratories that we suggested to our students are shown in List 1. In drawing up this list, we attempted to link PIBLs to both concepts (solubility, Ksp, activation energy, for example) and methods (titration, spectroscopy, calorimetry) discussed in the introductory chemistry course. Obviously, there are many possibilities for prompts, depending on the interests of the instructor. The list reflects our own backgrounds in environmental chemistry and geochemistry—areas that are particularly amenable to work in the field, as well as in the laboratory. The hope here was to combine in a single experience the rigor and craft of the traditional laboratory with the openness, uncertainty, richness, and excitement of inquiry-based learning and to do so at the skill level of the introductory course. From the outset, we encouraged students to “bend” our suggestions in ways that they might find appealing. We also allowed for the possibility that some students might choose to define, within
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In the Laboratory
limits of feasibility and within our resource base, their own research question. Generally, three categories of projects emerged from our list of suggestions: i. PIBLs that focused on local environments and that involved concepts or methods introduced in the scripted labs
List 1. Partial List of Prompted Inquiry-Based Laboratories 1. Location of regional ponds on R. J. Gibbs’s (9, 10) diagram of natural waters 2. Determination of the state of calcite saturation in a local pond 3. Examination of the pH of rainfall
ii. PIBLs that extended or elaborated upon the principles developed earlier in lab or in the lecture course itself
4. Analysis of variations of carbon monoxide levels with time in an urban environment
iii. PIBLs in which the student altered the suggested project, often taking it to a new level of sophistication
5. Determination of temperature effects on oxygen solubility in water
Most student projects fell into the first category (i). For example, one group spent the semester examining the concentrations of copper and bicarbonate in a local golf course pond. Since the pond had been treated by the algaecide copper(II) sulfate (a common practice in Florida) we wondered whether dissolved copper concentrations were controlled by the formation of insoluble copper carbonate phases. In addition to collecting uncontaminated filtered samples for copper analysis and measuring in situ pH, students were required to carry out equilibrium calculations on bicarbonate dissociation H+ + CO32−) and then to use the Ksp concept to (HCO3− determine whether or not CuCO3 was precipitating. While the project addressed a simple hypothesis concerning control of copper levels in an impacted water body, it nonetheless required that students integrate a relatively wide body of analytical and conceptual knowledge to address the question at hand. Some of the students who chose to work on local environments expressed surprise, indeed, delight that they could use chemical theory to address real-world problems. For many, it was the first time they had seen chemistry applied beyond the laboratory. A second group compared the composition of seawater with that of inland ponds and lakes with a view toward locating Florida waters on Gibbs’s diagram of worldwide water chemistry. In 1970, Gibbs (8) showed that most natural waters could be grouped into one of three categories, depending on the dominant mechanism of formation. Waters whose composition is controlled largely by rainfall (the Amazon and Orinoco Rivers, for example) tend to be quite dilute (low conductivity) and to exhibit a high Cl−兾HCO3− ratio. Waters whose composition reflects extensive bedrock weathering (the Mississippi River, the Great Lakes, waters draining calcareous terrain) generally have intermediate conductivities and low Cl−兾HCO3− ratios. By contrast, seawater and waters that have undergone significant evaporation (evaporation-dominated, in Gibbs’s terminology) are characterized by high conductivities and high Cl−兾HCO3− ratios. Students who undertook this project had an opportunity to explore the elements of geochemistry and to use in an inquiry setting the titration techniques that they had encountered earlier (Experiment 20 in Laboratory Experiments; ref 7 ) in their scripted laboratories. The project also gave them a more intimate chemical knowledge of local aquatic environments and highlighted the differences between marine and freshwater systems. It should be noted that projects in this first category tended to involve genuine discovery, in the sense that students were often obtaining new information that could not be located in any scholarly journal or regional report. We have found that this is often the case when studies focus on local 240
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6. Determination of the oceanic residence time of calcium and chloride 7. Assessment of temperature effects on the rate of decomposition of hydrogen peroxide 8. Determination of the dissociation constant of a weak acid as a function of ionic strength 9. Analysis of iron on the surface of seashells from different sedimentary environments 10. Heats of neutralization of mono-, di-, and tri-protic acids 11. Chemistry of the Lake Worth Lagoon as compared with the Atlantic Ocean 12. Errors associated with determination of Avogadro’s number using oleic acid 13. Creation of a silicon-rich fertilizer 14. Changes in pH and dissolved oxygen in a pond over a diurnal cycle 15. Nutrient release from decaying plant material 16. The rate of dissolution of calcium carbonate in distilled and carbonated waters 17. Iron oxidation and iron removal from a stream 18. Copper in local drinking water 19. Factors influencing gypsum solubility
environments. For students doing inquiry-based labs, the campus pond can be every bit as fascinating as the Atlantic or Pacific Ocean. Some students chose to extend scripted laboratories by altering the conditions of measurement (category ii). For example, Laboratory Experiments presents a scripted laboratory on the rate of decomposition of hydrogen peroxide at 25 ⬚C. By running this experiment at several other temperatures, students were able to determine the activation energy for this reaction. A second group of students used temperature variation to expand upon the laboratory on the determination of dissolved oxygen in water (Experiment 33 in Laboratory Experiments). This project was carried out using both the Winkler technique and a dissolved oxygen meter (YSI; http://www.ysi.com/index.html ) to determine oxygen solubility over a 70-degree temperature range. With their data, students were able to compute Henry’s law constants (assuming the partial pressure of oxygen in air at sea level) and then, by means of the van’t Hoff equation, the heat of solution of oxygen in water. In their writeup, the group emphasized both the environmental significance of their research (lower oxygen solubilities associated with higher water temperatures) and its theoretical content (Why, for example, does oxygen dissolve in water exothermically?).
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In the Laboratory
In some cases, prompted inquiry was expanded beyond the original designs of the instructors (category iii). One student team, for example, was intrigued by the composition of manganese nodules, a subject that had been introduced almost casually in a lecture on solid phases. We suggested that it might be interesting to examine the iron content of a single Pacific manganese nodule to see whether it was constant throughout (weight %) or whether it varied as a function of location (and presumably time of deposition) from center to periphery. Once a Pacific nodule had been obtained from Ward’s Natural Science (http://wardsci.com/), the project involved selecting an appropriate sampling strategy, dissolving the mineral in acid, and using the colorimetric method for iron outlined in Laboratory Experiments. The students—some of whom were concurrently enrolled in an introductory statistics course—examined their data for 16 samples using a two-sample t-test. Based on this approach, they were able to conclude that the sample was essentially homogeneous, despite the fact that it had probably formed over some tens of thousands of years. This self-directed extension of their research into the area of statistics was an important aspect of the project and it served to underscore the relationship between chemistry and mathematics. Among the advantages of PIBLs is the fact that they encourage students to link chemistry with other disciplines, including—in our experience— calculus, microbiology, oceanography, limnology, and environmental science. PIBL’s tended to reinforce the theme of Brown et al.’s text, namely, that chemistry occupies a central position among the natural sciences. Implementation The development and articulation of the PIBLs at the FAU Honors College were achieved largely through discussion between the instructors and the student research groups. These discussions were usually informal, although, on one occasion, we did have each group present a preliminary proposal to the class, followed by comments from students and instructors. Small class sizes at the Honors College (14–20 students) made this informal structure possible. We estimate that the instructors devoted, on average, about four hours to each group to ensure that students had a clear understanding of the problems they were addressing and the methods and equipment they were employing. In many cases, it was necessary to direct students to the geochemical, limnological, and environmental science literature to provide a context for their work. A more structured approach to inquiry-based learning has been developed by Cummins in his general science course for nonmajors (11). This more formal approach relies heavily on student feedback at several stages in the process and it may be more appropriate for large classes. Here, student teams submit their proposal to a Web site, where it is commented on extensively by both the instructor and other students in the course, revised, and then resubmitted in improved form. The critiques result in a refined proposal, a project, and, finally, a scientific paper and presentation. The key to this successful deployment of IBLs is constant monitoring by the entire class. Excellent, inquiry-based labs on Kepler’s Laws and the Moons of Jupiter, and on Effects of Land Use on Fish Populations can be found on Cummins’ Web site; these illustrate www.JCE.DivCHED.org
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the effectiveness of formal feedback at each stage of the process. Although it is more time consuming, we believe that Cummins’ strategy would also apply to both general chemistry laboratories and to courses for nonmajors. Regardless of the approach, formal or informal, we have found that it is important to organize student teams at the very beginning of the semester and to emphasize the need for background reading, project and hypothesis articulation, and group or instructor criticism. Conclusion In the first-year chemistry course, there really is no substitute for the rigorous approach offered by traditional scripted laboratories, regardless of how these are perceived (12). These laboratories link theory and experience and bring often rarified concepts to life and hence they should provide a framework for the introductory course. But in order that students come to fully understand science—either as part of their professional training or as an integral part of a liberal education—it is important that they experience firsthand the nature of inquiry. “The laboratory is not Merlin’s tower,” as Sayre (1) has noted, “and scientists are neither magicians nor seers”. Nor is the laboratory a kitchen, with a recipe book close at hand. Instead, it is the locus of both craft and invention, skill and creativity. Combined with scripted laboratories, inquiry-based learning can help students to understand this and to see that both craftsmanship and a spirit of exploration are essential to the scientific enterprise. In addition, inquiry-based learning can awaken an interest in science among those students who are not enthusiastic about standard approaches to laboratory. As one person noted, “I was amazed that I could formulate my own hypothesis and test it. I was actually being a scientist.” For many students, this direct participation in the scientific life can serve as an inducement to the future study of chemistry. Literature Cited 1. Sayre, A. Rosalind Franklin and DNA; W. W. Norton and Company: New York, 1975; p 16. 2. Widstrand, C. G.; Nordell, K. J.; Ellis, A. B. J. Chem. Educ. 2001, 78, 1044. 3. Gilbert, R. G.; Fellows, C. M.; McDonald, J.; Prescott, S. W. J. Chem. Educ. 2001, 78, 1370. 4. Wentzel, T. J. J. Chem. Educ. 2001, 78, 1164. 5. Rudd, J. A., II; Greenbowe, T. J.; Hand, B. M.; Legg, M. J. J. Chem. Educ. 2001, 78, 1680. 6. National Science Education Standards; National Research Council; National Academy Press: Washington, DC, 1996. 7. Nelson, J. H.; Kemp, K. C. Laboratory Experiments; Prentice Hall: Upper Saddle River, NJ, 2000. 8. Brown, T. L.; LeMay, H. E.; Bursten, B. E. Chemistry: The Central Science, 8th ed.; Prentice Hall: Upper Saddle River, NJ, 2000. 9. Gibbs, R. J. Science 1970, 170, 1088–1090. 10. Green, W. J.; Canfield, D. E. Geochimica et Cosmochimica Acta 1984, 48, 2457–2467. 11. NS1, fall 2002: Participatory Research in the Environmental Sciences. http://jrscience.wcp.muohio.edu/courses/ns1fallsyl01. html (accessed Oct 2003). 12. Domin, D. S. J. Chem. Educ. 1999, 76, 543–547.
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