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Mini-Journal Inquiry Laboratory: A Case Study in a General Chemistry Kinetics Experiment Ningfeng Zhao* and Jeffrey G. Wardeska Department of Chemistry, East Tennessee State University, Johnson City, Tennessee 37614, United States *
[email protected] Undergraduate chemistry courses are usually taught in an approach that focuses on memorization, rather than learning through inquiry (1, 2). Instead of reflecting the practice of scientific investigation, chemistry lab sessions are often designed for repetition and verification. Students follow the directions in the lab manual; perform the manipulations; record the data; and fill out a worksheet (3, 4). As a major strategy to improve student learning, inquiry-based science education is endorsed by National Research Council. The five essential features of inquiry-based learning encourage students to (i) engage in scientifically oriented questions; (ii) give priority to evidence; (iii) formulate explanations from evidence; (iv) connect explanations to scientific knowledge; and (v) communicate and justify the explanations (5-7). Despite the long history of inquiry in science education, and implementations of inquiry-based lab curricula (8-10), a vast majority of the college lab experiments are still highly structured, providing detailed research questions, experimental procedures, and result analysis (11). In addition, college faculty often resist inquiry-based instruction owing to limited understanding of inquiry, believing that students make all decisions of an investigation and viewing inquiry as unstructured and time-consuming (12). To recast the college science lab into an authentic and achievable inquiry-based format, we have developed the minijournal labs as a replacement of the traditional labs (13). The mini-journal mirrors scientific literature and consists of six sections including abstract, introduction, materials and methods, results, discussion, and citations. The mini-journal lab manual describes the investigation completed by the instructor, and the inquiry-based lab instruction models the work of scientists. Students read the mini-journal provided by the instructor (similar to scientific research), then design follow-up questions, carry out the investigation, collect and interpret the data (similar to scientific research), and finally communicate their findings in the form of their own mini-journals (similar to submitting a scientific paper) (14). Although students may not carry out an open inquiry where they make all of the decisions, they are engaged in the five essential features of inquiry in a field-based setting. For example, the mini-journal lab manual usually suggests follow-up research questions and students are guided to choose and engage in topics that are interesting to them. Through project “Connecting Undergraduates to the Enterprise of Science” (15), we and colleagues have implemented minijournal labs in a variety of science courses in different disciplines, including biological, physical, and earth sciences (14, 15). A case study of the mini-journal lab in a college chemistry curriculum, including the design of mini-journal lab manual, inquiry-based instruction, and reflections, is described. An experiment focusing on chemical kinetics and reaction order 452
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Figure 1. Reactions investigated in the chemical kinetics mini-journal lab.
was selected for several reasons. First, it is a common topic in most general chemistry labs. Second, kinetics theory is one of the most challenging topics in general chemistry. Finally, students usually have difficulties understanding the experimental design. In addition, the experiment has the potential to allow several follow-up questions for student investigation (see the minijournal lab manual in the supporting information). The Mini-Journal Lab Manual The reaction between hydrogen peroxide and iodide ion in an acidic environment, in the presence of thiosulfate ion and starch indicator (Figure 1), is examined. Iodide ion is oxidized by hydrogen peroxide to iodine, which is reduced back to iodide ion immediately by thiosulfate ion. With depletion of thiosulfate ion, the concentration of iodine will stabilize and form a blue color with starch. A traditional “cookbook” lab manual usually reviews concepts of chemical kinetics and reaction rate factors such as concentration, temperature, and catalyst. It provides detailed procedures of how to prepare reaction samples and record reaction times, followed by data tables and calculation formulas to determine the reaction order of each reactant, and observation protocols for temperature and catalyst effectiveness (16). As a result, manipulating a stopwatch and calculator are the only skills needed to complete the lab. The mini-journal lab manual studies the same reaction system and describes a complete investigation for determining the reaction order of hydrogen peroxide. A comparison of the traditional and mini-journal lab manual is shown in Table 1 with respect to the essential features of inquiry-based learning. The mini-journal lab manual starts with an abstract section summarizing the investigation and finding. The reaction rate expression and the research question of determining reaction order of hydrogen peroxide are presented in the introduction section and supported in the citations section. The materials and methods section provides details in experimental procedures. All experimental data are tabulated and graphed in the results section and followed by the analysis to determine the reaction order of hydrogen peroxide. The findings are justified in discussion section in the context of chemical kinetics, including possible sources of uncertainty and improvements. The mini-journal lab manual then suggests several follow-up
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In the Laboratory Table 1. Comparison between Traditional and Mini-Journal Lab Manuals Mini-Journal Lab Manual Traditional Lab Manual Review the overall chemical kinetics theory.
Essential Features of Inquiry Engages in scientifically oriented questions.
Determine reaction order of each reactant and effects of temperature and catalyst.
Sections Introduction and Citation: Reaction rate expression, research question of determining reaction order of hydrogen peroxide. Follow-up topics: reaction orders of other reactants, effects of temperature and catalyst.
Provide detailed procedures in sample preparation and reaction time recording.
Gives priority to evidence.
Materials and Methods: reaction sample preparations, multiple trials in data collection. Results: tables and graphs directly illustrating experimental data.
Provide tables and graphs for data arrangement and list calculation formula to find reaction orders and effects of temperature and catalyst.
Formulates explanations from evidence.
Results: determination of the reaction order of hydrogen peroxide. Discussion: conclusion of the reaction order based on results.
Report reaction order of each reactant as the results.
Connects explanations to scientific knowledge.
Discussion: justification of the finding in the context of chemical kinetics theory, sources of error and potential improvements.
No further explanation. Provide lab report pages
Communicates and justifies explanations. Abstract: summary of the investigation and finding.
Answer exercise questions.
Mini-journal format lab report.
investigations to determine reaction orders of iodide and hydrogen ions and the effects of temperature and catalyst on reaction rate. Inquiry-Based Lab Sessions The mini-journal lab was administered in an honors session of a second-term general chemistry course with 9 students. The goals were to introduce scientific inquiry and reinforce students' learning of chemical kinetics through inquiry. The mini-journal lab manual was given to students a week before the lab and they were explicitly informed that a different, more authentic approach to learning science would be implemented. Two lab sessions were required and the schedules are detailed in Table 2. Students in groups of 2-3 started to engage in the topics by reviewing the mini-journal lab manual at the beginning of the first lab session, referring to the following guide questions: • What are the research questions and why are they important? • What are the hypotheses? • What are the materials and methods for experimental investigation? • What data and evidence have been collected? • How are the data analyzed and what are the findings? Are they reasonable? • What are the follow-up research topics?
The questions were designed to introduce the process of scientific inquiry through a class discussion led by the instructor. In addition, the experimental method of determining the reaction order of hydrogen peroxide was introduced, as shown in the lab manual. It was important that students understood how to use the mini-journal lab manual and what the expectations for them were. The mini-journal lab manual served as a model of scientific research and reporting and also provided follow-up research topics. Using these topics as guidance, each group of students formulated their own research questions, and then designed, conducted, and reported their own investigations in
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the mini-journal format. During the first lab session, each group of students generated research questions and formulated hypotheses; designed material needs and experimental procedures; and outlined tables and graphs for data collection and analysis. They also practiced experimental techniques with glassware and instruments. The investigation plan of each group was then presented to the entire class. It helped clarify related research topics and promote collaboration between groups. For example, one group decided to investigate the reaction order of hydrogen ion and temperature effects, while another group selected the topics of reaction order of hydrogen ion and catalyst effects. These two groups commented on each other's plans and compared their results later on. On the basis of feedback and suggestions from the instructor and classmates, each group revised and finalized their experimental plans, which were approved by the instructor by the end of the first lab session. Students started the experimental investigation in the second lab session with supplied instruments and chemicals. They collected data; analyzed and evaluated results; trouble-shot procedures and recollected data if necessary; and formulated preliminary conclusions. The instructor interacted with each group and provided guidance throughout the entire investigation, especially in assisting students to evaluate experimental results and make connections to the context of chemical kinetics. Special attention was paid to unexpected experimental results and possible students' anxiety and frustration. For example, a common problem of the experiment is that the reaction sample could turn to blue before hydrogen peroxide was added, usually due to the contamination of glassware. These unexpected results created a unique learning opportunity for students. Instead of searching for “the” correct answer, it was more important to be able to evaluate and justify the results they obtained. The unexpected blue color could help students better understand the oxidation from iodide ion to iodine and clarify the importance of thiosulfate ion. After each group completed their investigations, they shared results and preliminary conclusions with the entire class, and looked for comparisons and suggestions.
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In the Laboratory Table 2. Lab Schedule First Lab Session Time/min
Students
Instructor
15.
Reviewed mini-journal lab manual
45
Replied to the guide questions
Introduced background of chemical kinetics and scientific inquiry, specified expectations for students in mini-journal lab Guided students to practicable research questions and hypotheses
Selected research topics, generated research questions and hypotheses 60
Developed detailed investigation plans and analysis procedures Practiced experimental techniques
Fostered discussion and team work
30
Presented group investigation plan Looked for comments and collaborations
Provided feedback for group plans Encouraged group collaborations
20
Revised and finalized investigation plan
Reviewed and approved group plans
Helped with related questions
Second Lab Session Time/min
Students
Instructor
90
Conducted investigation Summarized results
Assisted in experiment setup, data collection, and results extraction
45
Evaluated results, recollected data if needed Discussed and formulated preliminary conclusions
Helped explain and justify results and connect with research questions, hypotheses in science contexts
35
Shared results and conclusions Looked for comparison and comments
Summarized investigations Provided writing guide and grading rubric
Table 3. Brief Summary of a Student Group Investigation Research Questions and Hypotheses
What is the connection between iodide ion concentration and the reaction rate? An increase in temperature may exhibit a decrease in reaction time.
Investigation Procedures
Chemicals: DI water, acidic acid/sodium acetate buffer (0.05 M), KI (0.05 M), starch (3.0%), NaS2O3 (0.05 M), H2O2 (0.80 M), and acetic acid (0.30 M) Instruments: general purpose glass thermometer, one hot plate, two graduated cylinders (10 mL), ten beakers (250 mL), two glass stirring rods, a buret (10 mL), and a stopwatch. Prepare 3 reaction samples with different iodide ion concentration, 2 trials each. Prepare 3 reaction samples at different temperature, 2 trials each. Obtain average reaction time of each sample.
Presentation and Analysis of Results
Table of reaction time from each sample Graph of reaction time vs iodide ion concentration Graph of reaction time vs temperature Calculation of concentration and reaction order of iodide ion
Conclusions and Discussions
Concentration of iodide ion and the temperature have direct effects on reaction rate. The reaction order of iodide ion is calculated to be 0.5. Increase in temperature speeds up the reaction.
The brief summary from a student group investigation is shown in Table 3. At the end of the second lab, the instructor summarized the investigations and gave the students a writing guide and grading rubric for the mini-journal lab reports. Mini-Journal Lab Report and Grading Each student was required to write up his or her own minijournal lab report and peer-review was encouraged. Although the experimental section could be similar for group members, each student needed to interpret and justify the investigation individually. The mini-journal lab report summarized the overall investigation (abstract); provided subject background, research 454
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questions and hypotheses based on previous work (introduction and citations); described experimental procedures (materials and methods); presented quantitative results and illustrations (results); explained implications and possible sources of error and improvement (discussion); and connected the investigation in context of chemical kinetics (discussion). The mini-journal writing guide and grading rubric were developed to help students better understand the mini-journal format and expectations for their mini-journal lab reports (see mini-journal writing guide and grading rubric in supporting information). Each individual section of a mini-journal had a detailed description and a grading scale with estimated wordcount in the guide. It was stressed that the estimated words in the
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In the Laboratory
writing guide only provided an approximation, although succinctness and meaningfulness provided the keys of a scientific report. Explanations and discussions should be based on experimental evidence, in the context of chemical kinetics, including possible sources of error and potential improvements. Grading of the mini-journal lab report was focused on the complete scientific inquiry process, instead of any discrete correct answer. For example, the one student group reported that the reaction order of iodide ion was 0.5 based on the investigation and conclusion. The reported value agreed with the experimental results and fit into the kinetic theory, although the correct value should be 1. The students were credited for the investigation and explanations based on the results and referred to related studies for further learning. Reflections The mini-journal lab concerning chemical kinetics and the reaction order provided a successful inquiry-based learning experience for both the instructor and students. The instructor found that the major achievement of the mini-journal lab was student engagement. Well-designed follow-up research questions were crucial to fostering inquiry-based learning. These questions not only allowed students freedom to develop their own research topics, but also led to practical investigation and justification. In the future, mini-journal labs will connect to real-life experiences, providing a context for the investigation grounded in local or national problems. The overall quality of students' experimental design, data analyses and explanations, and mini-journal reports was impressive, as shown in Table 3 and student work in the supporting information. It was clear that through the model of mini-journal inquiry, students developed a better understanding and ability to conduct scientific inquiry, reinforced the learning of chemical kinetics, and applied critical-thinking and problemsolving skills. Although students were engaged in the topic with reinforced learning, their mini-journal reports still involved some common issues, as shown in the tables and graphs in the example mini-journal report in the supporting information. The first problem was the neglect of significant figures in analysis of the results. In addition, although the student realized the inversely proportional relationships between reaction time and reactant concentration and between reaction time and temperature, the data were incorrectly plotted as exponential functions. These problems could have been due to the miscalculation of reaction order with respect to iodide ion, and unfamiliarity with Excel software. However, they provided an opportunity to further student learning. Special attention needed to be paid to data analysis involving significant figures as they contributed to the experimental uncertainty. The instructor also linked exponential plots to the finding of reaction order and the Arrhenius equation to explicate the correct relationships between reaction rate and reactant concentration and between reaction rate and temperature. A post-lab survey was conducted with the students to explore their perceptions and to help improve the mini-journal lab in the future (see the student survey results in the supporting information). Most students had previous experience in college science labs, and all of them considered the mini-journal lab to be more interesting, creative, and requiring more independent thinking and problem-solving skills than traditional “cookbook”
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labs. The overall experience of inquiry-based investigations and mini-journal lab instruction and learning was satisfying, although some students indicated the difficulty of following the inquiry procedure and the discomfort of not knowing “the” correct answer. It was obvious that the transition from “cookbook” labs where students simply followed the prescribed steps, to mini-journal lab where they designed practicable investigations that logically followed the previous study, and justified the findings based on results in the science context, did not happen immediately. In addition, students recognized the extra workload involved in mini-journal labs, including pre-lab engagement, intensive discussion and group work, and effort in result analysis and mini-journal lab report preparation. However, students also realized the better learning and enjoyment of the mini-journal lab and preferred it to “cookbook” labs despite the higher requirements and workloads. Moreover, writing the mini-journal also helped students understand the format of scientific reporting. Although this case study was carried out in a relatively small classroom, it provided an insight of how inquiry-based lab can be incorporated into chemical education and benefit student learning. In a summary, mini-journal labs gave students experience not only in reading the scholarship of scientists, but also in doing and writing like scientists. Acknowledgment N. Zhao would like to dedicate this article to Sandra Abell (1956-2010), Curators' Professor and director of the University of Missouri Science Education Center, for providing guidance and insight to the field of science education. Special thanks go to Frank Schmidt, Professor of Biochemistry, Jan Weaver, director of the Program in Environmental Studies, John Adams, Curators' Teaching Professor of Chemistry, and Stephen Witzig in the Science Education Center at MU for their contributions to mini-journal inquiry. The authors thank Cassandra Eagle, Professor of Chemistry at East Tennessee State University (ETSU) for her suggestions to the manuscript, and ETSU for financial support. Literature Cited
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10. Kerner, N. K.; Lamba, R. S. Guided Inquiry Experiments for General Chemistry: Practical Problems and Applications; John Wiley & Sons, Inc.: Hoboken, NJ, 2008. 11. Buck, L. B.; Bretz, S. L.; Towns, M. H. J. Coll. Sci. Teach. 2008, 38, 52–58. 12. Brown, P. L.; Abell, S. K.; Demir, A; Schmidt, F. J. Sci. Educ. 2006, 90 (5), 784–802. 13. Park Rogers, M. A.; Abell, S. K. Sci. Educ. 2008, 92 (4), 591–607. 14. Witzig, S.; Zhao, N.; Schmidt, F.; Adams, J.; Weaver, J.; Abell, S. J. Coll. Sci. Teach. 2010, 39 (6), 14–23.
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15. CUES. CUES: Connecting Undergraduates to the Enterprise of Science. http://www.creativewebsolns.com/cues/ (accessed Jan 2011). 16. Postma, J. M.; Roberts, J. L., Jr.; Hollenberg, J. L. Chemistry in the Laboratory, 6th ed.; W. H. Freeman and Company: New York, 2004; Experiment 26.
Supporting Information Available Mini-journal lab manual; mini-journal writing guide and grading rubric; student mini-journal lab report; student survey results. This material is available via the Internet at http://pubs.acs.org.
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