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Problem-Based Learning: In Need of Supporting Materials Thomas J. Wenzel, Bates College
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need exists for published materials, preferably as additions or revisions to established textbooks and laboratory manuals, to support problem-based learning (PBL). A recent report on the undergraduate analytical chemistry curriculum recommends that instructors use PBL (1), but no commercially available resources exist. Instead, textbooks are designed to support a lecture format and provide mostly quantitative problems at the end of the chapters. Published laboratory experiments usually assess students on the accuracy and precision of analyses rather than giving them practice at analytical problem solving. In this column, I will address the types of published material needed by instructors to incorporate PBL into their lecture and/or laboratory courses.
TONY FERNANDEZ
Unit concept problems Chromatography is a common unit of chemistry that could benefit from PBL supporting material. The chromatography problems at the end of most textbooks usually involve quantitative determinations to ascertain the number of theoretical plates, plate height, capacity factor, and resolution. However, an analytical chemist working for a pharmaceutical corporation would likely be asked to develop analytical methods that detect the presence of trace impurities in a drug or metabolites in complex matrices. A PBL textbook could include questions that describe a range of samples in different matrices and require the students to choose and defend the selection of a
chromatographic method, detection technique, and mobile phase. Also, the problem could involve sample workup and the effects of mobile-phase conditions (pH, ionic strength, presence of
ion-pairing reagents, metal ion additives) on retention time and order. These types of questions would further develop the students’ problem-solving skills. Another example could be to provide poorly re-
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solved mixtures and ask students to select and defend their choice of the best parameter to improve their separation.
analytical chemists can solve problems without ever having to perform a chemical analysis, and that tests can be devised to confirm or refute a hypothesis.
Preferred-method problems Toward the end of a course, or after a chapter on techniques (e.g., spectroscopic methods), a series of preferredmethod problems could be given that ask what method would “best” identify or quantify a specific species in a particular sample. In answering such questions, students would need to know when fluorescence is recommended over absorp-
Collaborative learning problems Many undergraduate courses discourage group or collaborative activities; instead, they emphasize individual work. The most common justification for this is the need to assign an individual grade for the course to each student. However, individual projects do not properly prepare students for the teamwork that will be re-
The availability of published materials to support PBL methods would enhance the experience of students in undergraduate analytical chemistry. tion measurements, or when IR spectroscopy might be preferable to absorption or fluorescence methods. These types of queries require students to know the comparative strengths and weaknesses of analysis techniques. Students would also realize that several methods might work, and that the first choice may involve an assessment of the sensitivity, selectivity, ease of sample preparation, expense and time involved in the method, or the availability of certain equipment.
Real-world problems Procter & Gamble offers a PBL short course for undergraduates (2). Students in the course are presented with real industrial problems on which analytical chemists have worked. These problems initially require a broad assessment of the situation before determining whether a chemical analysis is necessary. However, real-world cases are needed in the classroom. Students could be given real problems and asked to devise possible questions and suitable methods to test them. On the basis of the students’ proposed methods for solving the problem, the instructor could then explain what would be learned from their test. Case studies such as these would demonstrate the breadth of questions one might ask about a problem and demonstrate that
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quired in their careers. Studies show that, for many students, collaborative learning is a better way to ascertain the material in a course (3, 4). Furthermore, using collaborative learning does not preclude assessing each student’s retention (5). Published collaborative learning exercises that support the material covered in analytical textbooks and indicate when an instructor might incorporate a short lecture component to summarize a concept or introduce an upcoming question would be helpful. Studies have shown that varying the presentation between lecture and collaborative activities enhances student engagement in the material (6, 7).
home pages of professors who practice PBL in the lab. The availability of published materials to support PBL methods would enhance the experience of students in undergraduate analytical chemistry courses. These materials would emphasize a broader set of skills for the students involved, as well as give an instructor the option to mix classroom and lab activities in a “classical” and PBL format or to convert to the PBL format completely. Thomas J. Wenzel is a professor at Bates College. Address correspondence to Wenzel at the Dept. of Chemistry, Bates College, Lewiston, ME 04240 (
[email protected]).
References (1)
(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
Laboratory approaches Many instructors believe that the primary place to conduct PBL in analytical chemistry courses is in the lab. Although several articles have been written on the use of PBL in the undergraduate analytical lab (8–21), most only provide brief descriptions of the experiments and methods used. Textbooks that cite published works on laboratory approaches to PBL would be beneficial. These textbooks could also include examples of methods applied to the analyses of environmental, forensic, industrial, biological, or material samples. Another possibility might be to create a Web site with links to the
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(13) (14) (15) (16) (17) (18) (19) (20) (21)
The report Curricular Developments in the Analytical Sciences can be obtained from Ted Kuwana, Dept. of Chemistry, University of Kansas, Lawrence, KS 66045 (http://www. chem.ukans.edu/analyt_curricular_dev). Thorpe, T. M.; Ullman, A. H. Anal. Chem. 1996, 68, 477 A–480 A. Wenzel, T. J. Anal. Chem. 2000, 72, 293 A–296 A. Wenzel, T. J. Anal. Chem. 2000, 72, 359 A–361 A. Wenzel, T. J. Anal. Chem. 1998, 70, 790 A–795 A. Wenzel, T. J. Anal. Chem. 1999, 71, 817 A–819 A. Ruhl, K. L.; Hughes, C. A.; Schloss, P. J. Teacher Education and Special Education 1987, 10, 14–18. Walters, J. P. Anal. Chem. 1991, 63, 977 A–985 A. Walters, J. P. Anal. Chem. 1991, 63, 1077 A– 1087 A. Walters, J. P. Anal. Chem. 1991, 63, 1179 A– 1191 A. Hughes, K. D. Anal. Chem. 1993, 65, 883 A– 889 A. Fitch, A.; Wang, Y.; Mellican, S.; Macha, S. Anal. Chem. 1996, 68, 727 A–731 A. Wright, J. C. J. Chem. Educ. 1996, 73, 827–832. Mabrouk, P. A. J. Chem. Educ. 1996, 73, A149–A152. Wenzel, T. J. Anal. Chem. 1995, 67, 470 A–475 A. Woosley, R. S.; Butcher, D. J. J. Chem. Educ. 1998, 75, 1592–1594. Settle, F. A.; Pleva, M. Anal. Chem. 1999, 71, 538 A–540 A. Wilson, G. S.; Anderson, M. R.; Lunte, C. E. Anal. Chem. 1999, 71, 677 A–681 A. Ram, P. J. Chem. Educ. 1999, 76, 1122–1126. Hope, W. W.; Johnson, L. P. Anal. Chem. 2000, 72, 460 A–467 A. Houghton, T. P.; Kalivas, J. H. J. Chem. Educ. 2000, 77, 1314–1318.
