Activity Cite This: J. Chem. Educ. XXXX, XXX, XXX−XXX
pubs.acs.org/jchemeduc
The Unknown Exercise: Engaging First-Year University Students in Classroom Discovery and Active Learning on an Iconic Chemistry Question Glen R. Loppnow* Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada S Supporting Information *
ABSTRACT: Scientific process thinking is usually lacking in first-year post-secondary general chemistry courses, as is a deep discussion of analytical techniques used to determine much of what we know about modern chemistry. A classroom activity is described here that brings the identification and characterization of a chemical unknown into the classroom, emphasizing self-directed, active, and teamwork learning within a social constructivist framework. In this way, the cognitive processes of identifying and characterizing an unknown can be emphasized separately from the psychomotor skills involved in the laboratory. Students work in pairs using self-directed learning to research the separation and characterization methods used by chemists. Each group advocates for a particular method, the class votes, and the instructor carries out the proposed method. The results are shown to the students (but not analyzed for them), and the cycle repeats until the unknown is identified. Students are assessed both individually and as a group. This activity was performed by 20−30 students in each of 3 years within two different first-year general chemistry contexts. Results show enhanced engagement in course and activity material and equivalent learning to lecturedelivered material based on assessment scores. KEYWORDS: First-Year Undergraduate/General, Interdisciplinary/Multidisciplinary, Collaborative/Cooperative Learning, Inquiry-Based/Discovery Learning, Problem Solving/Decision Making, Instrumental Methods, Qualitative Analysis, Quantitative Analysis
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tie the subjects together in these two first-year courses. The activity described here draws on pure chemistry knowledge and skills and should be easily implementable in any first-year postsecondary chemistry course. The identification and characterization of an unknown is a key concept emphasized in most post-secondary chemistry programs at both undergraduate and graduate levels. A scan of the literature1−3 shows that the vast majority of work has been done in the context of the laboratory and not the classroom. When an unknown has been brought into the classroom, it has generally been in the context of a single technique, such as NMR,4,5 and the particular technique is the focus rather than the broader scientific process. Curricular approaches that have emphasized process include process-oriented guided inquiry learning (POGIL)6−9 and, more recently, chemical thinking.10−12 POGIL is characterized by learning cycles of exploration− concept invention−application, whereas chemical thinking is founded on seven iconic questions of chemical content, phrased commonly in a “How do we...?” format. However, neither of these approaches emphasizes the scientific method, with its cycle of observation/results−hypothesis generation and refining−experiment that leads to a model of Nature, which is
INTRODUCTION There are questions that define chemistry as a distinct science, such as “What is that?”, “How much of it is there?”, “Why does that reaction proceed or not?”, and “How can this be made?”. These questions define the analytical, physical, and synthetic perspectives on matter. However, students in first-year chemistry are rarely exposed to these questions in detail, particularly the analytical techniques that are commonly used by practicing chemists to address the first question. Here, the identification and characterization of an unknown is described that takes place in the classroom environment, not the laboratory. This activity has been included in three separate classes of first-year university chemistry at the University of Alberta for 20−30 students per class, twice as a part of the full-year Science 100 (2010−2011 and 2011−2012), an interdisciplinary first-year science education comprising biological sciences, chemistry, computing science, earth and atmospheric sciences, calculus, physics, and psychology in an active learning environment, and once as a part of InSciTE (Interdisciplinary Science Threshold Experience, 2016−2017), a similar first-year interdisciplinary science education but which only involves chemistry, calculus, and either physics or biological sciences as the core science disciplines. Science 100 included a full year of general chemistry and the first term of organic chemistry, whereas InSciTE included only the first term of general chemistry. To be clear, the subjects are taught separately from each other, but there are interdisciplinary assessments that © XXXX American Chemical Society and Division of Chemical Education, Inc.
Received: November 8, 2017 Revised: April 27, 2018
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DOI: 10.1021/acs.jchemed.7b00852 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Figure 1. Scheme showing the analogy between the scientific method (top), with its ultimate outcome of a theory, and the unknown exercise (bottom), with its ultimate outcome of the identity of the unknown. The analogy between these two processes illustrates how multiple concepts can be taught within a single exercise on an iconic question in the discipline of chemistry.
advocacy and voting round (see below). Students are also told that they may need to spend some time outside of class on this activity in their groups doing background research. Once the unknown is introduced and students are in their groups, they go through a series of rounds (Figure 1 and Box 1)
one of the goals of this activity and a learning goal for the students.
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THE ACTIVITY In this activity, students work in groups of 4−5 to identify an unknown. In the first week of classes, students are required to complete a pretest, the Chemistry Concepts Inventory.13,14 Although no marks are given for this activity, it allows assigning groups that have diversity in their understanding of basic chemistry concepts. To assign groups, one student from the top quartile is put in each group, then one student from the next quartile is put in each group, and so on until the groups are full with four students each. Any remaining students are added to the first few groups so that some groups have 5 members, if necessary. Previous research has shown that having groups with such vertical diversity in ability or understanding can promote better peer−peer learning.15 Groups are not announced until after the unknown exercise is introduced. The unknown is typically introduced to the class within the second or third week of class (out of a 13-week term), after some practice with the various steps of the scientific method has occurred, particularly the observations/results step and the hypothesis generation step. This activity, the class is told, will be a term-long activity that will allow students to practice their scientific method skills by addressing two of the iconic questions in chemistry, “What is it?” and “How much of that is in it?”. The unknown is introduced with a story, typically one that involves disreputable or semilegal behavior on the part of the instructor. Such personal stories have been shown to foster a closer perceived student−instructor connection and have been also shown to enhance learning.16 Students are given the Separation and Characterization Sheet (Supporting Information), but no teaching intervention is performed on this activity; student learning is self-directed and reverse Socratic, with the students asking questions of the instructor. Students are told that they will work in their groups to try and solve the unknown. They are also told that they will have 10 min or so at the end of classes every now and then to either work together as a group or to do their
Box 1. Unknown Exercise Outline − 1 Round • Students discuss in their groups and make their choice of the next experiment to be performed. • One advocate is chosen in each group. • Advocates debate experiment choices in front of class. • Class votes. • Instructor performs experiment and posts results. in an attempt to identify the components and quantify them. A round is characterized by at least one 10 min session for the group to decide the next experiment they will advocate for, the advocacy speeches where a chosen advocate from each group states their group’s choice for the next experiment and why, a class vote on the next experiment, running that experiment, and posting the results. Experience has shown that a minimum of five rounds per term is needed for students to have a reasonable expectation of identifying and quantifying a three-component mixture, whether composed of liquids and/or solids. This number allows everyone in the group to be an advocate at least once and at least one opportunity for a “failed” experiment. Again, because this activity was targeted to first-year university students, the instructor performed the experiments and simply posted the results; students were responsible for the interpretation of the results. For more senior-level courses, students could potentially carry out some or all of the identification and quantification experiments in the laboratory. Indeed, unknowns are a wellknown component of almost any post-secondary chemistry program. Marking of the activity was done over two components. Students were individually marked on their advocacy speech, particularly on how well their reasons for the technique they B
DOI: 10.1021/acs.jchemed.7b00852 J. Chem. Educ. XXXX, XXX, XXX−XXX
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the listed techniques in this sheet with ones that are more applicable to that area.
chose supported the technique, logic, organization, and presentation poise and voice. These advocacy speeches were time-limited to 1−2 min but could be made longer or shorter depending on class size and instructor preference. The second component students were marked on was the quality of their endof-term group report on the exercise (Supporting Information). The weighting between these two assessments varied somewhat depending on whether the class successfully identified and quantified the unknown. If not, the end-of-term report could be assessed slightly higher than the individual component. In addition, exam questions can also probe this activity and the student learning that accompanied it. The instructor has used open-ended, optional exam questions such as “What may have been a better sequence of experiments chosen for the unknown exercise than the one used in class and why?” to allow students to reflect on the activity and for instructors to gain better insight into the learning that has occurred in the individual students.
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HAZARDS There are no hazards associated with this activity. RESULTS AND DISCUSSION There are several indicators that this exercise promotes engagement in learning chemistry and leads to longer-term retention of the learning outcomes explicitly emphasized in this activity. Student learning was assessed for the 2016 course on an individual basis via a required multiple choice question on the final, a bonus question on the final exam, and the advocacy talk that each student did during the rounds. In addition, student learning as a group was assessed via a required end-of-term report from each group on the status of the unknown identification and a post-class report from students who wanted to continue the exercise after the course was over. For the final exam questions, 100% of students (N = 25) attempted the required multiplechoice question (Box 2) with an average score of 72% (N = 18)
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EXPERIMENTAL PROCEDURE The unknown is not proscribed and could be anything. In the past, mixtures composed of only solids or both solids and liquids have been used. Typically, the components are in roughly equal amounts (on a mole basis) as this is usually students’ first exposure to an unknown, but proportions that are reminiscent of real-world samples may also be used. Because the activity was mainly targeted to first-year university students, mixtures in which the components have well-separated properties were used. For example, one year, a 1:1:1 mixture of sodium chloride/ potassium nitrate/guanine was used. For this sample, the difference in solubility between the sodium chloride and potassium nitrate compared to the guanine allowed for easy separation simply by water extraction, but the similarity between sodium chloride and potassium nitrate solubility made that separation an additional, more difficult challenge. For the class in which this particular unknown was used, the students never did successfully separate those two components but qualitatively identified them and quantified them via other means, including atomic absorption/emission, elemental analysis, and infrared spectroscopy. Providing acceptable levels of challenge in a group activity, particularly with scaffolding as in this example with solubility, can lead to lively discussion and more connection to the activity, leading to enhanced learning.17 Relevance can also be built into the mixture by adding in some locally relevant component. For example, if petroleum refining is a local activity, octane could potentially be a component in a liquid mixture. If mining is a locally or regionally important industry, the unknown could contain a metal ore or oxide as one of its components. By building this local relevancy into both the unknown and the story that introduces it, students may be more engaged. Access to analytical techniques is a prerequisite for this activity. Over the 3 years this activity was included in the instructor’s section of first-year university chemistry, the most popular techniques from the Separation and Characterization Sheet (Supporting Information) chosen by the students included elemental analysis, melting point, solubility, HPLC, atomic absorption/emission, mass spectrometry, and infrared spectroscopy. Thus, these techniques should be generally available to the instructor. Of course, the Separation and Characterization Sheet can be edited to those techniques that are available. Also, to use this activity in a materials or chemical biology course, for example, the instructor may wish to replace
Box 2. Required Multiple-Choice Final Exam Question: Of the following techniques for the unknown, the one that could separate the components is A. B. C. D. E.
HPLC. IR. Melting Point. CHNOS Analysis. AA/AE.
compared to a final exam average of 80.11 ± 12.75%. Although it is problematic to use student performance on a single question as a complete metric of learning, this result seems to indicate that this activity does not hurt student learning. The student average performance on the other multiple-choice questions of the final exam was 69.3% (N = 25), essentially the same as the performance on the unknown exercise multiple-choice question. Similar, although less impressive, results are seen for the optional final exam question. For this question (Box 3), 96% Box 3. Optional Bonus Final Exam Question: For the unknown exercise, the following order of analysis was determined by the class melting point, AA/AE, CHNOS analysis, quantitative AA/AE, HPLC Reorder the analysis techniques in a more optimal order, based on what you have learned from the unknown exercise. Justify and discuss your reordering. Identify the next technique, of the ones not chosen by the class for the unknown. Explain your reasoning for this new technique. (N = 24) of the students attempted, and the average score was 48.8 ± 19.3% for the students who attempted it. Students achieved an average of 52.8 ± 27.3% (100% attempted, N = 25) on the nonactivity optional questions. On the face of it, this is not a strong indication of effective learning, but the measurement of learning is complicated by the fact this was a bonus question, and it is not clear how student motivation to answer this question to the best of their abilities may alter the score as a clear measure of effective learning. C
DOI: 10.1021/acs.jchemed.7b00852 J. Chem. Educ. XXXX, XXX, XXX−XXX
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mentoring is an added enhancement to the peer discussions that occur within the groups.
Finally, each student group was required to submit a report at the end of the term as the unknown was unidentified at that point. The report simply asked students to provide their best estimate of the number of components and the percentage amount and identity of each component, referencing the experimental data and other course material as appropriate. The student groups scored 51.7 ± 23.2% on this report. Again, the average does not necessarily lead to the conclusion of effective learning, but the students were unsuccessful in identifying and characterizing the unknown. In other iterations of this exercise, students had the full year for this exercise and were successful in identifying and characterizing it. The low marks and the shorter time on the exercise for the 2016 class provided an opportunity to judge the engagement potential of this type of learning activity. To do that, the class was offered the ability to continue working on the exercise after the class ended. Because the class, as a cohort, was continuing on for the second semester in another course, this option proved feasible. Three of the six groups (N = 13, 52%) of the students continued on, even though no marks were assignable to this continuation. Two of the groups were ultimately and independently successful in identifying and correctly characterizing the unknown. There are a number of aspects of this problem that require comment. Students sometimes suggest separation and identification techniques which are not on the sheet accompanying the introduction of the unknown. Humorous examples include “Eat it”, “Drink it”, and “Snort it” as the first characterization methods. Although these are less than serious suggestions, they do provide an opportunity for discussing professional behavior by chemists when dealing with an unknown substance and how that has changed since Albert Hofmann’s day in 1943.18 Students selflearn how to interpret the data and results they receive; they are not taught the techniques in class. While students are surprisingly good at finding information on the Internet to be able to interpret data, they may make mistakes either due to rapid and imprecise skimming of the information or due to inexperience. The failure that results from these types of mistakes are recoverable in later steps, and I consider this learning to be something important students can take from this exercise. More serious is the lack of use of logic when analyzing the experimental results. In this analysis, students make novice mistakes, such as assuming that experiments are always completely successful and work as advertised. For example, students assumed that reverse-phase HPLC would separate components completely. However, for the example used here, the two ionic solids (sodium chloride, potassium nitrate) are very soluble in water and would not be retained at all on a hydrophobic column. Thus, seeing only one peak in the chromatogram led students to the incorrect conclusion that they were dealing with a pure substance. This incorrect conclusion dogged this particular class through most of the year until they performed a technique where they could see all three components distinctly. It was this realization that made all the other evidence clear, and a solution to the unknown problem quickly followed. This is perhaps the most significant cognitive trap that students fall into. Another problem that may come up is difficult group interpersonal dynamics. In three iterations of this exercise, difficult group dynamics have not been observed during this exercise, although it has been observed in other activities with the same class. Indeed, students from previous iterations of the exercise will often look over the current students’ work and provide helpful, but critical, comments. This intergenerational peer
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CONCLUSION An exercise has been described in which students, working in groups of 4−6, attempt to identify and characterize the chemical components in an unknown within the normal lecture portion of the class, emphasizing the cognitive aspects of the process rather than the psychomotor skills typically emphasized within the laboratory context. The learning is discovery-based, active, and completely student-directed. Assessment of learning occurred via marking of individual and group components through the advocacy speeches, final exam problems (both required and optional), and group reports. Results show that student learning via this activity led to similar performance on similar exam question types as the lecture-based material. In addition, instructor observations seem to indicate that the activity leads to more engaged and motivated learning of an iconic problem in the discipline.
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ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.7b00852. Separation and Characterization Sheet (PDF, DOC) Final Report Template (PDF, DOCX) Instructor’s Guide (PDF, DOCX)
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Glen R. Loppnow: 0000-0002-4630-8663 Notes
The author declares no competing financial interest.
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ACKNOWLEDGMENTS The author acknowledges the University of Alberta Teaching and Learning Fund for funding this project, the third-year instructors of SCI 100 at the University of Alberta (D. Lawrie, D. Vallee, B. Bachmann, W. Gallin, S. Yiu, P. Lu, K. Konhauser, G. de Vries, R. Sydora, and C. Varnhagen) for helpful comments, and the students of SCI 100 for their willingness to engage in learning science in new ways.
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REFERENCES
(1) Stock, N. L. Introducing Graduate Students to High-Resolution Mass Spectrometry (HRMS) Using a Hands-On Approach. J. Chem. Educ. 2017, 94 (12), 1978−1982. (2) Shuldburg, S.; Carroll, J. Scaffolding Students’ Skill Development by First Introducing Advanced Techniques through the Synthesis and 15N NMR Analysis of Cinnamamides. J. Chem. Educ. 2017, 94 (12), 1974−1977. (3) Williams, J. L.; Miller, M. E.; Avitabile, B. C.; Burrow, D. L.; Schmittou, A. N.; Mann, M. K.; Hiatt, L. A. Teaching Students To Be Instrumental in Analysis: Peer-Led Team Learning in the Instrumental Laboratory. J. Chem. Educ. 2017, 94 (12), 1889−1895. (4) Kurth, L. L.; Kurth, M. J. Synthesis−Spectroscopy Roadmap Problems: Discovering Organic Chemistry. J. Chem. Educ. 2014, 91 (12), 2137−2141. (5) Flynn, A. B. NMR Interpretation: Getting from Spectrum to Structure. J. Chem. Educ. 2012, 89 (9), 1210−1212.
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DOI: 10.1021/acs.jchemed.7b00852 J. Chem. Educ. XXXX, XXX, XXX−XXX
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(6) Moog, R. S.; Farrell, J. J. Chemistry: A Guided Inquiry; John Wiley & Sons: Hoboken, NJ, 2008. (7) POGIL | Home; http://www.pogil.org. (accessed April 2018). (8) Hunnicutt, S. S.; Grushow, A.; Whitnell, R. Guided-Inquiry Experiments for Physical Chemistry: The POGIL-PCL Model. J. Chem. Educ. 2015, 92 (2), 262−268. (9) Luxford, C. J.; Crowder, M. W.; Bretz, S. L. A Symmetry POGIL Activity for Inorganic Chemistry. J. Chem. Educ. 2012, 89 (2), 211−214. (10) Talanquer, V.; Pollard, J. Let’s Teach How We Think Instead of What We Know. Chem. Educ. Res. Pract. 2010, 11, 74−83. (11) Sevian, H.; Talanquer, V. Rethinking Chemistry: A Learning Progression in Chemical Thinking. Chem. Educ. Res. Pract. 2014, 15, 10−23. (12) Talanquer, V.; Pollard, J. Reforming a Large Foundational Course: Successes and Challenges. J. Chem. Educ. 2017, 94 (12), 1844− 1851. (13) Mulford, D. R.; Robinson, W. R. An Inventory for Alternate Conceptions among First-Semester General Chemistry Students. J. Chem. Educ. 2002, 79 (6), 739−744. (14) JCE Online: CQs and ChPs; https://www.chemedx.org/ JCEDLib/QBank/collection/CQandChP/CQs/ConceptsInventory/ Concepts_Inventory.html (accessed April 2018). (15) Johnson, D. W.; Johnson, R. T.; Smith, K. A. Cooperative learning: Improving university instruction by basing practice on validated theory. J. Exc. College Teach. 2014, 25, 85−118. (16) Maguire, J. The Power of Personal Story Telling: Spinning Tales to Connect with Others; Jeremy P. Tarcher/Putnam: New York, 1998. (17) Vygotsky, L. S. Mind in Society: The Development of Higher Psychological Process; Harvard University Press: London, UK, 1978. (18) Hofmann, A. LSD − My Problem Child; McGraw Hill: New York, 1980; pp 12−15.
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DOI: 10.1021/acs.jchemed.7b00852 J. Chem. Educ. XXXX, XXX, XXX−XXX
