In the Laboratory
Student-Directed Learning in the Organic Chemistry Laboratory Martha A. Hass Albany College of Pharmacy, Albany, NY 12208;
[email protected] The laboratory is an ideal environment for both active and cooperative learning (1, 2). Active engagement in laboratory exercises promotes a thorough understanding of concepts that lecture demonstrations or experiment descriptions fail to illustrate. A further enhancement of the laboratory experience can be gained by encouraging students to interact with each other during the discovery process (3). Cooperative learning is an established educational approach in which students work collaboratively in the development of methods to obtain, apply, and understand information. It has been incorporated into a number of educational settings and disciplines, including freshman general chemistry (4 ) and sophomore organic chemistry courses (3, 5). The reported benefits associated with group learning include improved performance on academic tests, improved proficiency in critical reasoning abilities, and the acquisition of communication and interpersonal skills (6 ). In view of the successes of these educational approaches, we implemented an active cooperative-learning strategy in the first semester of our organic chemistry laboratory. The experimental design, the results of this implementation, and a comparison of student performance with performance in more traditional approaches to laboratory instruction are presented in this report.
Evaluation Questions Used in Student Assessment of Experiments and Peer Performance Questions Used in the Evaluation of Group Member Performance Was the student prepared to do the experiment? Was he or she able to independently set up and conduct the experiment or was assistance required? If so, what level of assistance was necessary? Did the student contribute to the group in completing the worksheet and experiment assessment form? As a percentage of the total group, how much did this student contribute to completing the laboratory exercise? What grade (i.e., A, B, C, etc.) has this student earned for the work he or she did on this lab exercise?
Questions Used in the Evaluation of Coordinator Performance Was the coordinator prepared? Were the experimental procedures explained clearly and understandably? Did you understand how to do the experiment based on the coordinator's explanation? Was the coordinator able to help you with the actual setup and execution of the laboratory experiment? Were theoretical aspects of the experiment explained well? Were the coordinator's explanations accurate? Were there any factual errors in his or her explanation? Did the coordinator address questions from the group? If so, were they answered effectively? Did the coordinator rely on other group members to present the experiment or answer questions posed by the group? Did the coordinator speak clearly and in an organized fashion? Did the coordinator use charts, graphs, or diagrams to help explain the experiment? If so, were they useful? What grade (i.e., A, B, C ,etc.) has this student earned for the work he or she did on this lab exercise?
Methods
Questions Used in the Evaluation of the Experiment
Ten laboratory experiments (Table 1) (7) were performed using the cooperative laboratory format. Students worked in groups with peer direction, and instructors assumed the role of facilitator. The same ten experiments were also done using a traditional laboratory format in which students worked individually with the instructor’s direction. In both formats, one experiment was done per week. Students typically used the entire 3-hour laboratory session to conduct the experiment and record experimental data; other written assignments were done outside of the scheduled laboratory time. Table 2 outlines the design of the cooperative and traditional laboratory formats and highlights the differences between them. In the cooperative learning format students were randomly assigned to groups of three or four members, and group membership was maintained throughout the semester (8). Each week, one person in the group was assigned by the instructor to serve as experiment coordinator. The experiment coordinator had five major responsibilities, as shown in Table 2. At the end of each experiment, the students participated in peer assessment and assessment of the experiment. Group members assessed the performance of the coordinator and the coordinator assessed each group member. The questions used in the evaluation process are given in the box. Under both formats, students were required to complete written assignments for each experiment. Laboratory worksheets containing five to ten questions related to the
Did the lab text or prelab material provide adequate information and descriptions to allow you to conduct the experiment and complete the worksheet? If not, what information was missing? Did you use alternative sources to obtain this information? If so, list these sources. Was the experiment setup easy? difficult? Explain. Were chemicals, glassware, and equipment available and in good working order? Do you have any suggestions for supplies/equipment that would make this experiment run more efficiently? What did you learn from this lab exercise? Do you think you should have learned more? Do you think the principles or techniques used in this experiment will have any application in your educational or professional future? Explain.
theoretical aspects of the experiment, experimental design, and setup were collected one week after the experiment was completed. Worksheets generally required 1–2 hours of time to complete outside of the lab. In the traditional format students worked individually on these assignments, whereas in the cooperative format students were required to complete the assignments as a group. Laboratory notebooks were required and were graded three times during the semester. A single notebook grade was assigned for multiple experiments. In the cooperative format, one notebook was kept for the entire group, whereas individual students kept their own notebooks in the traditional format. Most of the laboratory notebook was completed in the lab. However the conclusion section was often completed outside of lab time and this typically required 30–60 minutes.
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Table 1. Experiments Done in Both Cooperative and Traditional Formats No. Experiment
Concepts/Skills
1
Melting Point Determination
Compound identification by melting point determination, melting point depression
2
TLC Analysis
Compound identification by chromatographic analysis, polarity
3
Solubility & Recrystallization
Polarity, filtration
4
Acid/Base Extraction
Acid/base reactivity and solubility behavior, Henderson–Hasselbalch equation, compound separation method by extraction
5
IR Spectroscopy
Compound identification by functional group determination, structure analysis
6
NMR Spectroscopy
Compound identification by carbon–hydrogen skeleton, structure analysis
7
UV Spectroscopy
Determination of concentration of solutions of unknown concentration, compound identification by UV active chromophore, Beer's law
8
Separation & Purification of Excedrin
Acid/base reactivity and solubility behavior, Hendersohn–Hasselbalch equation, compound separation method by extraction, analytical separation by TLC
9
Reactivities of Alkyl Halides
Determination of SN 1 and SN 2 reactivity
10
Drug Synthesis (Benzocaine, Acetaminophen, Aspirin)
Functional group manipulation, compound characterization by spectrophotometric methods, monitoring reaction progress by TLC
The duties of the laboratory instructor are summarized in Table 2. In the cooperative format, instructors evaluated each group’s written assignments and laboratory techniques and provided assistance to experiment coordinators with conceptual and technical questions. The coordinators were responsible for relaying this information back to the group. In both formats, the instructor presented theoretical aspects of many of the experiments in the lecture component of the course. Results Four assessment tools were used to evaluate the effectiveness of this teaching/learning approach and to compare it with a more traditional approach: (i) grades on written
assignments (worksheets and lab notebooks), (ii) qualitative peer evaluation, (iii) qualitative evaluation of experiments and experimental design by students, and (iv) the instructor’s perceptions.
Worksheet and Notebook Grades: Assessment of Content Knowledge Gained Grades on worksheets and notebooks were used to assess students’ content knowledge of the experiments. Performance on exam questions or laboratory practical exams related to the experiments was not used because these evaluation methods were not consistent during the two years of the study period. Average worksheet and notebook grades for students in the cooperative- and individual-learning formats are presented in
Table 2. Design and Comparison of Traditional and Cooperative Laboratory Formats Factor
Traditional Format
Cooperative Format
Experiments
353 students participated 10 experiments (see Table 1) 1 experiment each week Students worked individually
126 students participated 10 experiments (see Table 1) 1 experiment each week Students worked in groups
Group structure
Informal student interaction
2–4 students in each group Group members randomly assigned 1 group member served as experiment coordinator each week Role of coordinator rotated among members of the group each week
Student/group responsibilities
Experiment done by students working individually Written assignments done individually
Experiment coordinator responsibilities: present prelab lecture (15–20 min), delegate tasks (5–10 min), answer questions, hand in group assignments, assess group members (20–30 min) (see box) Group member responsibilities: carry out experiment, contribute to written assignments, individually assess experiment coordinator (90–120 min) Assess the experiment as a group (15–20 min)
Lab instructor responsibilities
Ensure laboratory safety Provide materials and equipment for experiments (45 min) Present prelab lecture (30 min) Answer all student questions (45–60 min) Supervise/direct student activities Grade individual written assignments and evaluate student laboratory techniques (5–8 hours/week)
Ensure laboratory safety Provide materials and equipment for experiments (45 min) Assign experiment coordinators (60 min/semester) Assist coordinators in answering student questions (20–30 min) Supervise overall group activities Assess group written assignments/ contribute to and coordinate student assessment (2–3 hours/week)
Written assignments
Individual notebooks (45–90 min) Individual worksheets (45–90 min)
Group laboratory notebook (20 min) Group worksheet (30 min) Group experiment assessment form (20 min) Individual asessment form
Grading and assessment
Individual grades determined by instructor based on written assignments and lab techique Overall course assessment by students
Individual grades determined by both peers and instructor based on group and individual work Overall course and experiment assessment by students
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Journal of Chemical Education • Vol. 77 No. 8 August 2000 • JChemEd.chem.wisc.edu
In the Laboratory
Figures 1 and 2. The data were analyzed statistically using an unpaired t-test and p values less than .05 were considered significant. Statistically significant differences in worksheet grades were noted in only three experiments (Fig. 1; experiment numbers are defined in Table 1). Notebook grades did not differ significantly between the groups, although the grades of students in the cooperative group were slightly higher (Fig. 2).
Group Assessment of Experiment The students generally felt that the written information provided was adequate and they were able to conduct the experiment effectively without excessive assistance or consultation from the lab instructor. They felt that the setup of the lab experiments was generally straightforward and easy. They usually accurately identified the purpose and underlying principles associated with the experiments. They overwhelmingly claimed they learned from each experiment. However, students had difficulty stating how they would apply the knowledge gained to a future educational or professional experience. Instructor Assessment Instructors felt the students learned the content of the experiments equally well in both formats. The major advantages of the cooperative format over the traditional format that were cited were (i) students were more independent in the laboratory; (ii) less time was spent answering the same individual questions; and (iii) there were fewer worksheets and notebooks to grade. The disadvantages of the cooperative format that were noted were (i) grading of assessment forms was time consuming and (ii) individual assessment of students was not possible. Discussion and Conclusions Evaluation of the students’ content knowledge was done using numerical grades on worksheet and laboratory notebook exercises. Students receiving instruction in the cooperative learning format performed as well on written laboratory assignments as those students in the traditional format. Comparison of the worksheet grades did not clearly show that
Figure 1. Comparison of worksheet averages using cooperative and individual learning methods. Open bars represent the cooperative approach and striped bars represent the traditional approach. *p ≤ .05. Experiment numbers are defined in Table 1.
Grade (%)
Peer Assessment Coordinators generally found group members well prepared to do the experiments. Most group members adequately contributed to the group and individual group members displayed competence and efficiency in their laboratory techniques. Group members reported that coordinators were usually prepared to present information about the experiment; however, in some instances, the coordinator’s explanations were not adequate. Early in the semester, students tended to be very generous in evaluations of their peers. Most coordinators assigned the same grade to all group members and only rarely was a member singled out and given a grade different from that of other members of the group. In general, the coordinators received better than average grades. As the semester progressed, however, the average grades declined. Students became more willing to freely express negative opinions about group members or coordinators, and this was reflected in the grades they assigned to each other.
Figure 2. Notebook averages using cooperative and individual learning methods.
one instructional method is superior to the other in leading students to an understanding of the concepts and techniques associated with each experiment. In seven of ten experiments there was no statistically significant difference in worksheet grades, nor was there any difference in notebook grades between the groups. These data suggest that students learn the same amount of material when they are allowed to direct their own laboratory exercises, with minimal guidance from the instructor, as when they are directed by an instructor. The peer evaluation process was designed to assess the students’ preparedness for the lab, their ability to work independently and to contribute to the group, their competence at experimental procedures, and their understanding of the experiment. Students were generally well prepared to do the experiments and most students regularly contributed to the group’s efforts. According to peer assessors, students had a strong conceptual understanding of the experiments. Initially, students were not comfortable with evaluating each other. They seemed to compensate for this discomfort by assigning better than average grades to their peers. However, as the semester progressed, students became more proficient at identifying strengths and weaknesses in their peers’ understanding and laboratory skills and were more willing to share
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In the Laboratory
their comments. As a result, they were better able to recognize their own strengths and weaknesses without the instructor’s direct intervention. While peer evaluation appears to be well suited to the cooperative learning environment because students work so closely together, future attempts at implementing peer assessment will most certainly put greater emphasis on teaching the students how to evaluate and provide constructive criticism to each other. Qualitative evaluation of the student-directed learning method by both the students and the instructors suggest many benefits that were not measured quantitatively. These include greater preparedness of the students before and during the lab exercise, and a shift from reliance on the instructor to answer questions to students seeking out answers from each other and from written sources. Overall, students enjoyed the independence and responsibility that this experience provided. This experiment in cooperative learning demonstrates that this format can be implemented in the laboratory without sacrificing students’ understanding of experimental concepts. It demonstrates that students are capable of organizing and directing themselves through a laboratory experience with proper supervision and guidance. The cooperative approach to laboratory instruction is continuing at our institution. We have extended the idea to include interactions between general chemistry students and organic chemistry students, and interdisciplinary experiments with organic chemistry and microbiology students. Long-term benefits have not yet been evaluated. However, as part of an institution-wide effort, we are working on assessment methods to determine whether this approach to instruction impacts students’ written and oral communication skills, organization, effectiveness as leaders, and ability to design strategies for solving scientific problems.
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Journal of Chemical Education • Vol. 77 No. 8 August 2000 • JChemEd.chem.wisc.edu
