Article Cite This: J. Chem. Educ. XXXX, XXX, XXX−XXX
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Using a Guided-Inquiry Approach To Teach Michaelis−Menten Kinetics Jesse A. Phillips,† Gregory H. Jones,†,‡ and Erin V. Iski* Department of Chemistry and Biochemistry, University of Tulsa, 800 South Tucker Drive, Tulsa, Oklahoma 74104, United States
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S Supporting Information *
ABSTRACT: Although kinetics forms a foundational part of the chemical curriculum, laboratory experiences with the subject are often limited and lack relevance to the actual practice of chemistry. Presented is an inquiry-based lab focused on Michaelis− Menten kinetics, implemented in an upper-level, university physical chemistry laboratory. Student learning was assessed over the course of three years via a pre- and post-test scheme that evaluated student understanding of Michaelis−Menten concepts and experimental design. Results indicate improvement in both domains, in line with previous results in the inquiry-based laboratory literature. KEYWORDS: Upper-Division Undergraduate, Physical Chemistry, Inquiry-Based/Discovery Learning, Enzymes, Kinetics
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INTRODUCTION The traditional and still widely practiced methods of teaching chemistry separate the curriculum into lecture and laboratory components, with the lecture striving to provide a solid theoretical understanding and the laboratory reinforcing the concepts presented in lecture. Beyond the most elementary chemistry courses, laboratory courses also serve to facilitate the applied practice of chemistry. Many lab experiments are primarily designed to achieve the first goal (reinforcement of lecture material), and although they teach about the usage of chemical apparatus and instrumentation, they neglect the fundamental principle of science in practice: inquiry. This system of educating students, which is used in practically every science discipline, can start as early as elementary school and is a way to incorporate both lecture material and practical knowledge into the curriculum. Although quite successful at allowing students to work toward predetermined results, this approach is severely flawed in wholly cultivating young scientists as it fails to promote the use of the scientific method to investigate unknown systems.1−7 In response, higher learning institutions have begun to incorporate inquiry-based laboratories into their curricula as a means to address these issues.1,8−10 Undergraduate chemistry standards have also begun to follow suit. Guidelines set forth by the American Chemical Society (ACS) state that an undergraduate chemistry curriculum should include pedagogies that have been shown to be effective in undergraduate chemistry education, specifically citing inquiry-based learning.11 Rather than focusing on rote memorization of a technique or method to then verify through expository laboratories, inquirybased laboratories help students focus on critical thinking and realistic problem-solving techniques in the form of proposing their own hypotheses, designing and performing experiments, and evaluating and explaining results. Studies have shown that these methods are more effective at developing an understanding of experimental design and limitations while promoting autonomy in the lab.8,11,12 These skills are essential © XXXX American Chemical Society and Division of Chemical Education, Inc.
for students’ future careers as scientists in industry or research.8−10,12−14 Kinetics is often one of the first subjects taught in general chemistry as an “anchoring concept”, because it relates deeply to other ideas such as chemical change, equilibrium, and thermodynamics.15−17 However, students are often not exposed to laboratory kinetics until late in their undergraduate career.18,19 This is likely because expository laboratories do not lend themselves to the exploration of kinetics, as the students often struggle to understand the purposes of the various techniques and procedures used. Inquiry-based laboratories turn this problem on its head, directly involving the students in experimental design and requiring a full understanding of techniques, procedures, and expected results and how they fit together to answer a scientific question. Recognizing the eminent suitability of inquiry for teaching kinetics, we developed and implemented a guided inquiry lab exploring enzymatic kinetics and inhibition. This lab was systematically improved over the course of 3 years and involves two iterations driven by student performance.
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STUDENT BACKGROUND The enzymatic kinetics lab was designed to be administered within the third quarter of the Physical Chemistry 1 Laboratory (170 min lab), which accompanies the Physical Chemistry 1 Course (50 min lecture). All participants were students enrolled simultaneously in both the Physical Chemistry 1 Course and the Laboratory or students who had taken the lecture course previously. The group of enrolled students comprised almost entirely junior-level chemistry and biochemistry majors from a small private university in the lower Midwest. Breakdowns of the student demographics by major and gender can be found in the Supporting Information (Tables S1 and S5). Received: January 11, 2019 Revised: May 10, 2019
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DOI: 10.1021/acs.jchemed.9b00031 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Figure 1. Comparative performance between Iterations 1 and 2. Error bars reflect a 95% confidence interval computed using 1000 bootstrap samples.
rubric and assessment were updated as described below for Iteration 2. Each iteration is discussed at length below, but a summary detailing the data comparison for Iterations 1 and 2 can be seen in Figure 1. The rubrics, the pre- and post-test assessments, and the prelab questions are available in the Supporting Information (SI). When reviewing the studentsupplied responses, the questions were graded by a single individual to ensure consistency across all graded material. Student names were given numerical values to codify individuals and protect their identities during grading, such that the names of the individuals were unknown to the grader at the time of evaluation. Given that evaluation of higher-level, free-response questions contains an inherent level of subjectivity, scoring was standardized by the grader grading a single question across all tests before moving to the next question. Once the pre-assessments were completed, the students performed the experiments over a two-week period. At the beginning of the third week, the postlab assessment was administered within the same 30 min time limit to ensure consistency between both tests.
Both chemistry and biochemistry students had exposure to enzyme kinetics through lecture courses prior to the laboratory experience. Biochemistry majors take an Introduction to Biochemistry course in their freshman year, which briefly discusses enzymes as catalysts but does not discuss inhibition or the Michaelis−Menten equation. Furthermore, we estimate that more than 95% of both chemistry and biochemistry majors take the Biochemistry I lecture course concurrently with the Physical Chemistry I lecture and lab. Biochemistry I covers Michaelis−Menten kinetics via Lineweaver−Burke plots as well as competitive and noncompetitive inhibition prior to lab implementation. The Physical Chemistry I lecture also covers Michaelis−Menten kinetics, Lineweaver−Burke plots, and all types of inhibition. As the latter covers these topics almost simultaneously with the lab, small variances in lecture pacing may manifest in assessment results. Alternate regression methods were not discussed in any chemistry or biochemistry courses prior to the lab.
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EXPERIMENTAL DESIGN The experiment was performed in two iterations, where insights from the first iteration were used to improve the design of the second experiment. The design of the experiment followed a standard pre- and post-test assessment format in which students spent the first 30 min of the first session completing a pre-assessment test. This test was used to determine their general knowledge of the subject matter as well as their ability to independently devise an experiment to investigate the proposed question. In order to ensure that all of the students were exposed to the pertinent chemical kinetics material necessary to succeed, prelab questions were assigned the week before. These questions were suggested for completion in Iteration 1 but were required for a grade in Iteration 2. Iteration 2 also added a question that required students to design an experiment to determine the Vmax and Km for an uninhibited enzyme as preparation for their first week of lab. An additional set of prelab questions in preparation for the second week of lab was also included in Iteration 2. The responses to the pre-test assessments were scored on the basis of a rubric devised by the authors. This
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HAZARDS AND SAFETY PRECAUTIONS
The substrate used in this laboratory, pGlu-Phe-Leu pnitroanilide (PFLNA), is not considered to be a hazardous substance or mixture. However, in creating the substrate solution used for the experiment, PFLNA is diluted in DMSO and, therefore, should be handled with gloves as well as the appropriate protective eyewear. Furthermore, when completing the inhibitor portion of the lab, students are given five separate inhibitors to work with, some of which are fairly concentrated acids or bases (6 M) that must be diluted before administration to the experimental solution. Again, lab goggles as well as gloves are necessary when attempting this laboratory to ensure student safety. In some cases, the lab instructor may prepare the necessary solutions at the appropriate concentrations for students, if concerns arise. Additionally, this lab requires the use of papain in its solid state, which is classified by Sigma with the signal word “Danger” and, therefore, should be handled with care. Students should wear lab goggles and gloves when handling papain to prevent exposure to the skin or B
DOI: 10.1021/acs.jchemed.9b00031 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Table 1. Mean Scores on Pre- and Post-tests for Iteration 1a Question Pre-test Score (%) Post-test Score (%) Difference (Pre-test − Post-test) (%)
1
2
3
4
5
Overall
36 ± 6 69 ± 5 33
6±2 41 ± 6 35
22 ± 3 39 ± 4 18
14 ± 3 37 ± 3 23
15 ± 3 22 ± 2 6
19 ± 2 38 ± 3 19 ± 2
a
Error quoted is standard error of the mean.
enzyme kinetics. In particular, they were asked to quantitatively characterize how these inhibitors changed the Km and Vmax values and to determine qualitative aspects of the inhibition (reversibility, competitiveness, etc.). A copy of the lab handout can be seen in the SI. Following the completion of the second week of the laboratory, students were given 1 week to write a full-length lab report of roughly 1500 words. Each student independently wrote their own lab report. These reports were prepared in the same form as those of all other laboratories during the semester. An example lab report is included in the Supporting Information. On the due date of the lab report, students were given the postlab assessment and allotted 30 min to complete it. All assessments were taken independently.
eyes. Also, when working with papain, students should work under a well vented hood to prevent any respiratory issues. Beyond these specific examples, there are no other significant hazards associated with this lab.
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IMPLEMENTATION Students were first given access to a set of prelab questions a week before the lab session via e-mail to familiarize them with the various math and chemistry concepts that would be needed during the 2 week labtime frame. At the beginning of class during week 1, students were given a prelab assessment to be completed within 30 min. After the students finished their prelab assessment, they began the experiment with a very basic lab handout, included in the SI, which served as a general guide for a pair of students to design an experiment. During the week in between sessions 1 and 2, students were e-mailed the second part of the prelab questions, which is included in the SI. These were to be completed before the week 2 session began. Finally, after the students completed both lab sessions, they were required to turn in an independent lab report the following week and take the postlab assessment at the beginning of the next lab period. Over the course of the 2 weeks allotted for this lab, the students designed experiments to test the chemical kinetics of the enzymatic reaction between papain (Sigma P3169-25MG), a cysteine protease enzyme, and pGlu-Phe-Leu p-nitroanilide (PFLNA, Sigma P3375-25MG), a protease substrate.20−24 Both chemicals were purchased through Sigma. The first week’s session focused on measuring basic Michaelis−Menten parameters (Km and Vmax) in the absence of inhibition, whereas the second week explored the effects of inhibition on the system. The basic lab handout in week 1 contained a “Base Procedure”, which contained information on sample preparation and an initial set of concentration conditions as a starting point. Student pairs were then asked to design and execute their own experiments to determine the rate of the hydrolysis and to choose a regression method for the data analysis. The choice of regression method was key in a student’s ability to properly visualize and quantitatively analyze the data. The different regression methods (e.g., Lineweaver−Burk, Hanes− Woolf, nonlinear, etc.) have various associated advantages and disadvantages, and each student determined which approach or combination of approaches would provide the most reliable results and effectively communicate the data.19,20,22−24 From these regression analyses, students were able to determine values for the Km (Michaelis−Menten constant) and Vmax (maximum rate achieved under saturated substrate concentrations) parameters of the Michaelis−Menten model of enzyme kinetics.23 In the second week of lab, student pairs selected an inhibitor from an array of inhibitors revealed upon their arrival and designed experiments to test the associated effects on the
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RESULTS AND DISCUSSION
Iteration 1
Summary of Assessment Data. Responses from 37 students were analyzed over the course of two years for Iteration 1, and the results are summarized in Table 1 and Figure 2. Data was collected only for those students who were
Figure 2. Score breakdown by question for Iteration 1. Error bars reflect a 95% confidence interval computed using 1000 bootstrap samples.
present for both the pre- and post-assessments. The assessment consisted of five free-response questions, which were used to not only determine the student’s understanding of the basics of chemical kinetics but also their ability to scientifically approach a hypothesis and to develop a means to investigate that hypothesis. The average score of the students before completing the lab was 19% with a standard error of 2%, consistent with prelab assessments in other inquiry-based laboratories.14 After completion of the lab, the students were given the same assessment, which was graded using the same rubric. These tests had no impact on student course grades. Overall, the students increased their average score by 19 percentage points on the post-test relative to the pre-test. C
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between competitive and noncompetitive inhibition, but a lack of understanding of uncompetitive inhibition propagated through all three parts of this question. Of the three parts of this question, students’ scores were the lowest on part b, where they were to give a chemical rationale for the changes or lack of changes in Km and Vmax relative to the inhibition type. We attribute this artificially low score to an incongruency between the question and the rubric. The rubric required an explanation for why an unchanged value remained the same, whereas the question only asked to “give a chemical rationale for the changes”. Question 4. Q4: Evaluate the advantages and disadvantages of the Lineweaver−Burke plot and/vs. a nonlinear regression for visualizing and quantifying Michaelis−Menten kinetics and inhibition data. Give contexts in which each of these methods might be useful. Question 4 assesses student knowledge of acquired laboratory skills at DoK level 3 and utilizes the “Evaluate” cognitive process. This question showed significant improvement, in line with the focus of the laboratory experiment. Most students were able to identify the advantages and weaknesses of Lineweaver−Burk plots, but they said little about the nonlinear regression method. Lower absolute scores are due to most students only listing one advantage or disadvantage where the rubric required at least two. Question 5. Q5: Design an experiment to determine whether a known enzyme inhibitor displayed a reversible noncompetitive mode of inhibition or an irreversible mode of inhibition. Make sure to describe how the results of the experiment would differ for these two modes of inhibition. Question 5 asked students to employ the “Create” cognitive process at DoK level 3 and to design an experiment like the one they designed in week 2 of the lab. The question focused on distinguishing only two different modes of inhibition because of the time constraint of the assessment; however, the two modes selected were difficult to distinguish because of their similar effects on Km and Vmax. As such, successful understanding of the level of Question 3a would be insufficient to design an experiment to differentiate those inhibition types. This question is quite difficult, and a perfect-score answer requires a solid grasp of both the content knowledge and principles of experimental design, in particular the ability to devise a test to distinguish between two similar possibilities. Although most students could design a control experiment, none were able to design an experiment that effectively distinguished between the two modes of inhibition. The question was unable to really probe experimental design principles because of a lack of content knowledge necessary to design the experiments. Many students confused the irreversibility of the inhibition with the irreversibility of the enzyme−substrate reaction and designed experiments to test the reversibility of the latter.
Subgroup analysis based on gender and major showed no significant differences in improvement or overall performance between groups (Figures S2−S4). Low overall scores on the test are inherent to the structure of the rubric, which was designed to have a wide dynamic range, differentiating student performance at both the highest and lowest levels. The authors estimate that a score of 60% would reflect a traditional letter grade of A. The assessment given is not recommended for summative evaluations at other universities. Keeping in line with the design of the rubric, the following analysis will discuss the post-test assessment and focus on improvement in scores as opposed to absolute scores. Assessment of Learning. Questions 1 and 2. Q1: Write the equation for the Michaelis−Menten model of enzyme kinetics and give a brief (1 sentence or less) description of each term that appears. Q2: Define the following terms: IC50, Ki For the first two questions, students were asked to define specific values and constants that are of importance in chemical kinetics. As the lab requires a full understanding of the subject material in order to design and execute experiments, one would expect improvement on lower order thinking skills and expression (“Remember” in the Anderson−Krathwohl taxonomy; level 1 question in Webb’s Depth of Knowledge, DoK), even if these definitional concepts are not directly emphasized.25,26 This idea is borne out by the data, with students showing improvements of 33 and 35 percentage points on each question, respectively. The extreme improvement in Question 2 over Question 1 is due to significant pre-test knowledge in the basics of Michaelis−Menten kinetics. Basic Michaelis− Menten kinetics had been covered in the lecture course, but inhibition had not been discussed in detail. The most common mistakes observed in Question 1 were the reversal of the definitions of Km and Vmax. On Question 2, some students were unable to define IC50, and Ki was described solely as “an equilibrium constant” without further elaboration. Question 3. Q3: a, Compare and contrast competitive, uncompetitive, and noncompetitive inhibition in terms of their effects on apparent Km and Vmax values. (Hint: a chart might do well to answer this question.) Q3: b, Give a chemical rationale for the above changes in Km and Vmax in terms of the mechanisms of these inhibition types. Q3: c, Describe how these inhibitors change the Lineweaver−Burke plot for a given enzyme. The third question assesses student understanding of inhibition at DoK level 2 and requires multiple different levels of cognition (“Remember”, “Analyze”, and “Apply”, for a, b, and c, respectively). It is the most similar of the lab questions to typical assessments of knowledge in lecture courses and probes the ability of the guided inquiry lab to teach new content knowledge, as enzyme inhibition was only briefly discussed in the lecture course. Students performed well on Q3, showing an increase of 18 percentage points in their understanding of enzyme inhibition; however, this increase is the lowest among the lab questions, reflecting the overall focus on developing new skills in experimental design over content knowledge. This result suggests ways in which laboratory and lecture learning can supplement each other’s strengths while emphasizing complementary skills and understanding.27 Question 3 revealed some weakness in the understanding of uncompetitive inhibition. Most students could distinguish
Iteration 2
Although Iteration 1 of the lab experiment could be used to show an improvement in both overall knowledge of Michaelis−Menten kinetics and experimental design, the magnitude of growth left something to be desired. Experience gained through implementation suggested the following modifications, which were used to create a new iteration (Iteration 2) of the lab. D
DOI: 10.1021/acs.jchemed.9b00031 J. Chem. Educ. XXXX, XXX, XXX−XXX
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Table 2. Mean Scores on Pre- and Post-tests for Iteration 2a Question Pre-test Score (%) Post-test Score (%) Difference (Pre-test − Post-test) (%)
1
2
3
4
5
Overall
43 ± 8 84 ± 5 41
11 ± 5 49 ± 7 38
24 ± 4 53 ± 4 29
30 ± 4 48 ± 7 18
15 ± 3 44 ± 3 29
23 ± 2 52 ± 3 29 ± 2
a
Error quoted is standard error of the mean.
(1) Many students came into the first laboratory session for this experiment unprepared. In order to address this, a set of prelab questions (SI) was assigned as a graded homework exercise 1 week before the start of the lab. (2) The wording of some of the responses in the post-test results of Iteration 1 indicated some degree of student apathy to the assessment instrument, having no relevance to the course grade. This was rectified by administering a grade for the assessment, which eliminated the issue, and the overall quality of responses increased. It should be noted that the distributed preassessment erroneously stated that it was not for a grade, although verbal instruction at the time of administration corrected that mistake. (3) Field testing of the assessment instrument with chemistry and biochemistry department faculty revealed wording ambiguities in some of the test questions. These questions were reworded to improve clarity. The rubric element addressing a control experiment in Question 5 was adjusted from a binary response (whether it was present or not) to a sliding scale, indicating the quality of the proposed control.
Figure 3. Score breakdown by question for Iteration 2. Error bars reflect a 95% confidence interval computed using 1000 bootstrap samples.
ineffective, the post-test scores for Question 1 show a significant increase in understanding in Iteration 2. This is attributed to better preparation for the laboratory experience, allowing students to get more out of their time in lab. Question 3. As the prelab questions covered all of the information in Question 3, it is surprising that pre-test scores are essentially flat between the iterations; however, students again showed significantly improved post-test scores. This improvement was specifically reflected in part b, the section concerning the molecular basis for various types of inhibition. This provides further evidence that inquiry-based laboratories also effectively teach foundational scientific knowledge in addition to experimental design principles. Questions 4 and 5. Question 4 was the only question where significant increases in the pre-test scores were observed between the iterations. As only Lineweaver−Burke regression is discussed in the biochemistry and physical chemistry course taken by the students, the prelab questions were likely the students’ first exposure to alternate regression schemes in Michaelis−Menten kinetics. Question 4 is also the only question that was modified for Iteration 2 with the substitution of the word “and” with “vs.” in an attempt to clarify to the students the proper comparative approach for the answer. It is believed the combination of this clarification with the prelab questions worked to boost student performance on this question. Question 5 showed a much greater increase in understanding of experimental design. Students provided better controls and experimental protocols that actually distinguished between the two types of inhibition. The prelab questions likely encouraged students to begin thinking in terms of distinguishing the inhibition types, knowledge of which was solidified in the laboratory experiments. Students still failed to explicitly compare the experimental results to their control, although given the quality of the rest of the response, they would likely have done this in practice.
Summary of Assessment Data. With the implementation of Iteration 2 of the experiment, responses from 20 students were analyzed over the course of 1 year, with the final results outlined in Table 2. As with Iteration 1, data was collected only for students who completed both the pre- and postassessments. The same five questions and grading rubric, minimally adjusted as mentioned above, were used for the preand post-assessment analyses. Students again showed an increase in overall scores and averaged nearly 30 percentage points better with a standard error of 2% after completing the inquiry-based laboratory following the modifications set forth in Iteration 2. Further subgroup analysis based on gender and major again showed no significant differences in improvement as it related to these subfields, and that data can be seen in the Supporting Information (Figures S6−S8). Assessment of Learning. As with Iteration 1, Iteration 2 was subjected to the same pre- and post-assessment analysis with nearly identical rubric criteria for grading. The overall increase in score for Iteration 2 was nearly 30 percentage points, and although that is only a 10 percentage point increase from Iteration 1, there was an interesting shift in points from the old model to the new. Scores began to show increases in Questions 1, 3, and 5 that were much larger than those seen for these questions in Iteration 1. The full breakdown of each question will be discussed below and can be seen in Table 2 and Figure 3. Questions 1 and 2. Pre-test results on Questions 1 and 2 indicate little change in preknowledge of the lab in comparison with the student responses in Iteration 1. Although this might suggest that the inclusion of the prelab questions was E
DOI: 10.1021/acs.jchemed.9b00031 J. Chem. Educ. XXXX, XXX, XXX−XXX
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FUTURE DIRECTIONS
ASSOCIATED CONTENT
* Supporting Information S
Although the data show that this laboratory experiment has aided learning in enzyme inhibition kinetics as well as in experimental design, there still exist areas for improvement. Although changes in the rubric for Question 5 helped better capture student learning, the question is admittedly difficult. This question will be altered in future versions of the lab in an attempt to better probe the intended learning objectives. Furthermore, online simulation tools may be included in future versions as part of the prelab experience. The addition of simulation tools, such as those implemented at the University of Illinois28 or Kintek Explorer,29 can illuminate certain key aspects of Michaelis−Menten kinetics. Students could benefit from observing the plotting of data in real time as well as from seeing how changing certain parameters, such as Km, enzyme concentration ([E]0), and substrate concentration ([S]0), can dynamically affect the observed plots. Although nonlinear curve fitting is the method of choice for determining the Michaelis−Menten and inhibition parameters, most textbooks only discuss Lineweaver−Burke plots in detail. Whereas the current student analyses utilized more reliable linearization methods, most did not utilize nonlinear regression. In the true nature of the “guided” aspect of guided inquiry, students might in the future be required to compare the results of a nonlinear regression to the results of various linearization methods. Nonlinear regression is now easily accomplished using off-the-shelf solutions already available at many academic institutions, such as Origin or KaleidaGraph. Finally, leveraging larger sample sizes along with employing more extensive analysis of qualitative data from the lab reports will guide further iterations in accordance with a spirit of a dynamic and evolving design.
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Article
The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.9b00031. Michaelis−Menten Student Handout (PDF) Instructor Guide (PDF, DOCX) Michaelis−Menten Student Lab Report Sample (PDF) Michaelis−Menten Assessment Iteration 1 (PDF) Michaelis−Menten Assessment Iteration 2 (PDF, DOCX) Michaelis−Menten Prelab Questions Iteration 1 (PDF) Michaelis−Menten Prelab Questions Part 1 Iteration 2 (PDF) Michaelis−Menten Prelab Questions Part 2 Iteration 2 (PDF) Pre-assessment Rubric Iteration 1 (PDF, DOCX) Pre-assessment Rubric Iteration 2 (PDF, DOCX) Supplementary figures for student distribution by major and gender, pre-test results by major and gender, posttest results by major and gender, and improvement by major and gender for Iterations 1 and 2 (PDF)
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Erin V. Iski: 0000-0003-3375-299X Present Address ‡ G.H.J.: Arthur Amos Noyes Laboratory of Chemical Physics, Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, United States
Author Contributions
CONCLUSION
†
J.A.P. and G.H.J. contributed equally in the preparation of this manuscript.
The literature over the past few years has shown very positive approaches to learning through the inquiry-based method of teaching at an undergraduate level. Because of the complexity of chemical kinetics, it can become difficult to properly ensure that the students obtain and process the information during the course of a single lab. By incorporating inquiry into the design of a kinetics lab, we were able to not only simplify arcane lab procedures but also develop student skills in experimental design. Furthermore, although students had some prior exposure to enzyme kinetics concepts, this activity was able to engage them at higher levels, requiring creation of new ideas via designing experiments as well as iterative evaluation of results to make decisions about their next experiment. We believe this level of engagement is necessary to solidify understanding of the content knowledge and to develop practical skills in experimental design. This work also serves to highlight the advantages of data-driven iterative design and continual improvement of laboratory activities to facilitate greater student learning. Weaknesses identified in Iteration 1 were addressed in Iteration 2 with noticeable improvement in student learning. Data from Iteration 2 have already elucidated targets for a third iteration. Given its ability to facilitate learning of both content knowledge and experimental design, we hope this lab can join the growing body of resources for effectively teaching chemistry in its most natural form: inquiry.
Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS The authors gratefully acknowledge the financial support from the Chemistry and Biochemistry Department at The University of Tulsa. J.A.P. was supported in part through the Graduate Research Grant Program through the Office of Research and Sponsored Programs at The University of Tulsa. G.H.J. was supported through both the Chemistry Summer Undergraduate Research Program and the Tulsa Undergraduate Research Challenge offered through The University of Tulsa. The authors thank William Potter, Robert Sheaff, Jason Martin, and the physical chemistry students for their input.
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DOI: 10.1021/acs.jchemed.9b00031 J. Chem. Educ. XXXX, XXX, XXX−XXX
