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A comparison of student performance in multiple-choice and long essay questions in the MBBS stage I physiology examination at the University of the West Indies (Mona Campus)
Dagogo J. Pepple,
Lauriann E. Young, and
Robert G. Carroll
01 JUN 2010https://doi.org/10.1152/advan.00087.2009
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Abstract
This retrospective study compared the performance of preclinical medical students in the multiple-choice question (MCQ) and long essay question components of a comprehensive physiology final examination. During the 3 yr analyzed, 307 students had an average score of 47% (SD 9.9) in the long essay questions and 64% (SD 9.9) in the MCQs. Regression analysis showed a significant correlation (r = 0.62, P < 0.01) between MCQs and long essay questions. When student performance was grouped by final course grade, a statistically significant correlation between MCQ and long essay scores existed only for the 210 students who received a passing grade (r = 0.20, P < 0.01). The MCQ and long essay question scores were not correlated for the 57 students who failed (r = 0.25, P = 0.06) or for the 40 students who achieved honors and distinctions (r = −0.27, P = 0.11). MCQ scores were significantly higher (P < 0.01) than essay scores for each of the groups when analyzed by two-way ANOVA. The results of this study suggest that for most students, the strong correlation between scores on MCQs and essay questions indicates that student performance was independent of testing format. For students at either end on the performance spectrum, the lack of correlation suggests that the performance in one of the testing formats had a strong influence on the final course grade. In addition, those students who failed the course were likely to be weak in both testing modalities, whereas students in all grade groups were more likely to perform better in the MCQs than in the long essay questions.
assessment of learning is often one of the more difficult and time-consuming aspects of education. In physiology instruction in the preclinical years of medical school, knowledge is usually what is assessed. Course grades are a form of summative assessment, usually as a result of performance on examinations. Instructors have a variety of examination formats to use for student assessment, each with unique characteristics.
Multiple-choice questions (MCQs) are a common type of assessment due to their reliability, validity, and ease of scoring (5). MCQ tests are often constructed to assess the students' ability to recall isolated pieces of information rapidly. There have been some suggestions, however, that competent students may perform poorly in MCQs because of their ability to read more into the questions than the examiners intended (1).
Another common type of assessment is open-ended, long essay questions. This format allows students more flexibility in their response and reflects their individuality of approach in which interpretative skills can be evaluated (6, 15). Essay questions also allow specific feedback to direct future learning (7). Nnodim (11) reported that MCQ papers were less sensitive predictors of the aggregate performance than essay questions, whereas Day et al. (4) observed that essay questions, although valid, failed to measure aspects of competence over and above those measured by MCQs.
The use of multiple formats for a single student assessment is labor intensive (3, 5). The additional labor may be justified if the formats test unique aspects of learning (14). If so, student scores in one format may not be tightly correlated with student scores in a different format. Some studies have reported statistically significant correlations between MCQ and essay scores in physiology continuous assessment tests (13) and short essay questions (10).
Before the implementation of the system-based curriculum at the University of the West Indies (UWI; Mona Campus), the comprehensive final examination in physiology had both essay and MCQ components. Because each component was weighted equally in calculating the final course grade, this provided an opportunity to compare student performance on the two testing formats. We analyzed historical data to determine if there was a correlation between the performance of our failing, passing, honors, and distinction students in the MCQs and long essay questions in the comprehensive final examination in physiology.
MATERIALS AND METHODS
This is a retrospective study involving 307 students who took a comprehensive final examination in physiology in 1997, 1998, and 1999. The data were collected from files in the Department of Basic Medical Sciences. There were 111 students in 1997, 94 students in 1998, and 102 students in 1999 who took the physiology examinations. The study was approved by the Ethics Committee of the Faculty of Medical Sciences of UWI (Mona Campus). Confidentiality was maintained as there was no disclosure of the names of the students from whom the data were derived.
Institutional setting.
UWI is an international institution serving the Commonwealth countries of the Caribbean. It began as the University College of London in 1948 and achieved full university status in 1962 with authority to grant its own degrees. The Faculty of Medicine at the Mona Campus, which began in 1948 (now named the Faculty of Medical Sciences), was modeled on the British system and awards the Bachelor of Medicine and Bachelor of Surgery degree after 5 yr of study. Course grades are also modeled on the British system, where <50% is a failing grade, 50–64% is a passing grade, 65–70% is an honors grade, and >75% is a distinction grade. This grading system is very different from the standard 10-point scale used in much of the United States, where <70% is a failing grade, 70–79% is a grade of "C," 80–89% is a grade of "B," and >90% is a grade of "A."
Examination formats.
Before the implementation of the systems-based curriculum in 2001, the final examination in physiology was taken at the end of the 2-yr preclinical training. It had both essay and MCQ components.
The essay component of the final examination lasted 2.5 h. Students were presented with six open-ended questions, where they selected five questions and had 30 min to write on each of them. The MCQ component of the final examination consisted of 150 questions with a duration of 3 h. The MCQ paper was divided into three sections. The main section consisted of questions with one best answer out of four options. Two smaller sections included questions with one or more answers out of four options and a statement and reasoning area. Both the essay and MCQ modalities had equal weighting and contributed 75% to the final score for each student. The remaining 25% of the final score for each student was the average of three in-course examinations. A viva voce (oral) examination was given only to those students who were on the border line of pass/fail (i.e., those achieving a score between 45% and 49%) and those who were being considered for honors or distinction (i.e., those achieving scores between 60% and 64% and between 70% and 74%, respectively).
Data analysis.
The data were analyzed with the SPSS statistical package and are reported as means (SD). A Kruskal-Wallis test was used to identify any variation in scores between classes over the 3 yr of data collection to determine if the aggregate student performance could be combined to provide a larger sample size for analysis. Pearson's correlation coefficient (r) was calculated to determine if performance on the essay question was correlated to the performance on the MCQ score for each group. Finally, two-way ANOVA followed by Tukey's test was used to determine both the impact of examination format (MCQ vs. essay) and the final course grade (fail, pass, honors/distinction) on student performance. The level of significance was set at P < 0.05. During the period of this study, item analysis was not performed on the MCQ examinations at UWI.
RESULTS
Analysis of the data revealed no statistically significant differences in student performance in the 3 yr studied; hence, the respective MCQ and essay scores were combined and analyzed for the 3 yr under review. Because of the small number of students who had distinctions, their scores were grouped together with those who had achieved honors.
Regression analysis showed a significant correlation (r = 0.62, P < 0.01) between MCQs and long essay questions. When students were grouped by final course grade, a significant correlation between MCQ and long essay scores existed only for the 210 students who received a grade of passing (r = 0.20, P < 0.01). The MCQ and long essay question scores were not correlated for the 57 students who failed (r = 0.25, P = 0.06) or for the 40 students who achieved honors and distinctions (r = −0.27, P = 0.11).
MCQ scores were significantly higher (P < 0.01) than essay scores in all grade groupings when analyzed by two-way ANOVA followed by Tukey's test. The detailed data are shown in Table 1.
Enlarge tableTable 1. MCQ and essay scores for students who failed, passed, and achieved honors/distinctions in the second Bachelor of Medicine and Bachelor of Surgery physiology examination
Enlarge table
Figure 1 shows scatterplots of the aggregate student performance. As indicated in Table 1, there was a significant correlation between essay and MCQ scores for the entire group. MCQ performance was stronger than essay performance for all but five of the students.
Fig. 1.Scatterplot of aggregate student performance in the second Bachelor of Medicine and Bachelor of Surgery (MBBS) physiology examination. MCQs, multiple-choice questions.
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Figures 2–4 show examination performance broken down by course grade. For many of the students receiving a final passing grade (Fig. 2), the stronger MCQ performance compensated for a failing grade in the essay component. This pattern was repeated for students receiving honors/distinctions (Fig. 3). For students who failed the examination, the poor performance on the essay component was strong enough to offset a passing grade on the MCQ component (Fig. 4). Only one student who ultimately failed the examination had a passing score on the essay component.
Fig. 2.Scatterplot of students who passed the second MBBS physiology examination.
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Fig. 3.Scatterplot of students who achieved honors and distinctions in the second MBBS physiology examination.
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Fig. 4.Scatterplot of students who failed the second MBBS physiology examination.
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DISCUSSION
The most important finding of this study was that there was a statistically significant overall correlation between student performance on MCQ and essay examination scores. The correlation between long essays and MCQ scores indicated that, in general, students who performed well in the essays were also likely to do well in the MCQs. Oyebola et al. (13) and Moqattash et al. (10) noted a similar relationship in the performance of their students.
We also observed that scores for MCQs compared with long essay questions were consistently higher in all groups, that is, students who had failed, passed, or received honors/distinctions. The average difference in the scores was 12 points for the group of students who failed the overall examination and was even larger for the other groups. It is worth mentioning that the correlation between long essay scores and MCQ scores for students who failed may not have achieved statistical significance (P = 0.06), partly due to the small sample size (n = 57) of this subgroup. A future study with a larger sample size might help to clarify this doubt. However, the effect of a small sample size may not be responsible for the lack of correlation observed in the students who achieved honors and distinctions, even though they had a similar sample size (n = 40). This is due to the nonsignificant P value of 0.11 in this subgroup.
As schools modify their assessment approach, this type of difference in student performance can have a significant impact on the final grades earned in a course. This difference is likely not limited to this student population, as a lower performance in the physiology long essay questions, particularly when the question lacked cues, was also noted by McCloskey and Holland (9).
An interesting finding is that there was no correlation between long essay and MCQ scores for those students who performed at honors and distinction levels. We interpret this to mean that the more competent students had unique strengths in either one or the other examination format. For example, students with strong factual recall abilities may have scored higher in the MCQ component, whereas students who had strong analytical or interpretative skills, and an ability to organize and apply knowledge, were able to score higher in the essay component of the examinations. Anbar (1) also observed a lack of correlation in the performance of competent students in MCQ tests compared with open-ended tests and a positive correlation for the less competent students.
The consistently lower scores in the long essay questions may be attributed to the bias or more subjective marking schemes of different lecturers compared with the more quantitative nature of MCQs. A similar observation of higher scores in MCQs and short essay questions compared with structured, integrated long essays was reported by Moqattash et al. (10), who indicated that one of the reasons for the higher scores was the elimination of examiners' bias. However, we believe that long essay-type assessment is a sensitive test requiring students not only to recall facts but also to use higher-order cognitive skills, such as analytical, interpretive, and application skills.
The scores on the MCQ component were much lower than would be expected for examinations in the United States system using a 10-point grading scale. The minimum performance for passing in the British grading system is 50%, in contrast to the 70% minimum passing grade for United States schools. Despite the different scales, internal and external review of curriculum and student performance have emphasized the validity of the grading schemes using the standard setting (2, 12), particularly when determining the pass/fail threshold. An interesting exception to the 70% passing grade in the United States is the licensing examination of the National Board of Medical Examiners, where the pass/fail threshold is often close to 56% of items answered correctly (8).
In summary, this retrospective study indicates that, in general, there was a strong correlation between student performance in MCQs and long essay questions. This suggests that the additional effort used to prepare examinations in both formats may not be justified. There was no correlation between MCQ and long essay scores for either the more competent students or the students who received failing grades. Thus, student grades determined by an examination format that includes both testing modalities may be different than the grades obtained by using only one of the modalities. The overall higher performance in all groups of students on the MCQ examination indicates that without the long essay examination format, some of the failing students may likely have passed the final examination in physiology.
DISCLOSURES
No conflicts of interest, financial or otherwise, are declared by the author(s).
AUTHOR NOTES
Address for reprint requests and other correspondence: D. J. Pepple, Dept. of Basic Medical Sciences (Physiology Section), The Univ. of the West Indies, Mona Campus, Kingston KgN 7, Jamaica (e-mail: dagogo.pepple@uwimona.edu.jm).
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Volume 34Issue 2June 2010Pages 86-89
Copyright & PermissionsCopyright © 2010 the American Physiological Society
https://doi.org/10.1152/advan.00087.2009
PubMed20522902
HistoryReceived 24 September 2009
Accepted 20 January 2010
Published online 1 June 2010
Published in print 1 June 2010
Keywordsmedical education
student assessment
physiology
Bachelor of Medicine and Bachelor of Surgery
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How We Teach
Singing greeting card beeper as a finger pulse sensor
Gregor Belušič, and
Gregor Zupančič
01 JUN 2010https://doi.org/10.1152/advan.00015.2010
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Abstract
We constructed a robust and low-priced finger pulse sensor from a singing greeting card beeper. The beeper outputs the plethysmographic signal, which is indistinguishable from that of commercial grade sensors. The sensor can be used in school for a number of experiments in human cardiovascular physiology.
the human cardiovascular system offers numerous attractive experiments in human physiology at all levels of education. Time-resolved cardiovascular parameters can be relatively easily obtained by measuring the heart rate (HR) via ECG or finger pulse (FP) and the blood pressure (BP) with a sphygmomanometer. Computer-aided data acquisition nevertheless requires the proper galvanic separation of measurement instrumentation and the use of sensors that are not always available to the teachers. During a training course in human physiology for Slovene secondary school teachers, we realized that virtually all of them had access to instruments for computer-aided recordings such as LabPro or LabQuest by Vernier Software and Technology (5), usually shared with physics and chemistry teachers. Yet only a few of them had an ECG or other suitable sensors, so that they were very limited in their ability to record the parameters related to cardiovascular system functions. However, every Vernier instrument is, by default, equipped with a voltage probe, which allows the connection of appropriate voltage sources in the range of ±10 V with clips. We assumed that a suitable signal for such a system could be provided from a FP sensor. We constructed a low-cost sensor with a robust signal, proposed a few experiments for its application, and presented the sensor with the experiments to the teachers. The teachers positively accepted the proposal, learned how to construct the sensor themselves, and how to make recordings with it. The whole system is currently being implemented as part of the biology course in Slovene secondary schools.
MATERIALS AND METHODS
We assumed that a plethysmographic signal from fingers can be detected with a contact microphone firmly attached to a finger. A contact microphone, as such, is not necessarily required since any loudspeaker can, in principle, serve as a microphone. Several gadgets and toys contain such cheap loudspeakers. Our source was several different "singing" greeting cards, costing between 1 and 5 euros each, bought at the local post office (music modules for greeting cards manufactured by Tianyu Electronics, Shenzen, China). The cheapest cards contained conveniently sized (25 mm diameter) piezoelectric beepers, whereas the more expensive "polyphonic" cards came with somewhat larger (40 mm diameter) electromagnetic speakers. We tried both types and found that the polyphonic speakers produced outputs that required a substantial amplification before analog-to-digital conversion and were, therefore, not the best suited for school use. In addition, they also delivered a poor signal, most likely due to displacement and immobilization of the coil in the finger-attached position, and were thus inferior to the piezoelectric beepers that we used in all the experiments described. These rigid piezoelectric speakers are especially well suited as contact microphones since they output relatively high voltages upon deformation and hence do not require any amplification, making them especially suited for school work. A quick online survey indicated that the beepers can be found within greeting cards worldwide. If not sold locally, greeting cards can be bought from internet retailers and shipped to practically all countries. Piezoelectric beepers alone are also available in different sizes and housings from online hobby electronic shops.
The beepers' wires were detached from the electronic circuit, and the beepers were removed from the greeting cards. The beepers are housed in a plastic shell on one side, forming an acoustic cavity. The opposite side of the beeper can serve as the surface of a contact microphone. In some greeting cards, the beepers had a piece of soft plastic, 2–4 mm thick, attached to this side to dampen the very annoying sound produced when the speaker was in direct contact with the paper of the greeting card. Although it is not absolutely necessary, we found that this plastic actually also improves the recordings by concentrating the pressure on a smaller area of the finger. A beeper was secured with Leucoplast adhesive tape to a finger so that the exposed metal side with the soldered wires was in contact with the skin. To stabilize the signal, we constructed a simple passive resistor-capacitor (RC) high-pass filter with a 1-μF capacitor and 100-kΩ resistor soldered to a stripboard, yielding a 1.6-Hz cutoff frequency. This alternating current filter is not absolutely necessary since the beeper itself acted as a high-pass filter with a 0.3-s time constant. It was, however, useful to reject any direct current offsets and drifts, which often appeared in this low-cost device. The filter was soldered to the speaker terminals. The terminals were connected with the voltage probe clips to the LabQuest interface (Vernier) or with crocodile clips to a Powerlab 4/25T (ADInstruments). The sensor constructed from the beeper, wires, and a high-pass filter is shown in Fig. 1.
Fig. 1.A: finger pulse (FP) sensor assembled from the beeper and passive resistor-capacitor (RC) high-pass filter. The beeper side contacting the finger is shown oriented upward. A piece of soft rubbery plastic, which originally connected the beeper to the greeting card, was intentionally left on the beeper surface to improve the contact between the finger and sensor. The RC filter's resistor and capacitor terminals are exposed to facilitate the connection of the clips. Inset: scheme of the sensor. The speaker icon represents the beeper. B: the beeper sticked to Leucoplast tape and the forefinger. The tape is glued to the plastic housing. C: the beeper secured to the proximal portion of the last segment of the forefinger.
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RESULTS
The volume changes due to the pulsed blood flow in the finger resulted in a large voltage signal coming from the beepers' terminals. The beepers were able of delivering up to 0.7 V peak to peak. We found that all the beepers suffered from large and drifting offset potentials (up to 2 V). We corrected the offset potentials and stabilized the signal by inserting a simple passive RC high-pass filter (cutoff frequency = 1.6 Hz) between the beeper and terminal wires (see materials and methods). The filter distorted the signal slightly by picking a few millivolts of the 50-Hz mains noise, but this did not substantially degrade the quality of the recording (Fig. 2, middle; signal = minimum 160 mV peak to peak, mains noise = maximum 5 mV peak to peak).
Fig. 2.FP of a subject performing the Valsalva maneuver. The vertical lines at 4 and 40 s indicate the time of the beginning and end of the maneuver; abdominal pressure was further increased at 30 s. Top: FP detected with the commercial-grade sensor (MLT 1010, ADInstruments). Middle: FP detected with the sensor constructed from the beeper and RC filter. Bottom: heart rate [HR; in beats/min (bpm)] calculated from the middle. Insets at the top and middle show a magnified portion of the FP signal from the three heart beats preceding the maneuver. Changes in blood pressure are compensated through the changes in HR via the baroreceptor reflex.
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An example of a FP recording is shown in Fig. 2. Two sensors were attached to the two forefingers of a subject performing a Valsalva maneuver: a commercial-grade sensor (MLT 1010, ADInstruments) to the left forefinger (Fig. 2, top) and the beeper to the right forefinger (Fig. 2, middle). The plethysmographic signal from the beeper was virtually indistinguishable from the signal coming from the commercial-grade sensor. Both signals performed equally well in sensing and recording the main characteristics of the FP: multiple peaks due to elasticity of the arterial system and the signal size proportional to systolic BP. In both cases, this allowed for automatic peak detection and online calculation of HR (Fig. 2, bottom).
DISCUSSION
FP sensors allow teachers to perform a number of measurements and experiments in the classroom. The following are some examples:
The multiple peaks of the FP can be used to illustrate the Windkessel effect, BP wave reflection, and their relation to age, atherosclerosis, and hypertension (1, 3).
The FP signal can be used to demonstrate the measurement of systolic BP. FP can be obstructed with a sphygmomanometric cuff inflated to a pressure above the systolic BP, so that the sensor can partially substitute a stethoscope, and the obstruction of the FP can be observed on the screen.
The contribution of hydrostatic pressure to BP can be demonstrated by repeating systolic BP measurements with the hand elevated or lowered.
The amplitude of the FP follows systolic BP and the state of peripheral vasodilatation, both of which are related to stress, cold, etc. FP amplitude, the size of the secondary peak, and the interval between the primary and secondary peak can serve as a rough indicator of the changes in systolic BP.
The automatic (and, if possible, online) detection of HR from the FP allows one to monitor the effects of exercise on the cardiovascular system, to observe respiratory arrhythmia, and to perform more complex experiments, such as the diving response or Valsalva maneuver (2, 4).
GRANTS
The training course for the teachers was supported by the European Union through the European Social Funds, Operative Program of Human Resources Development 2007–2013, Developmental Priorities: Human Resources Development and Life-Long Learning, Improvement of Quality and Effectiveness of Systems of Education and Training.
DISCLOSURES
No conflicts of interest, financial or otherwise, are declared by the author(s).
AUTHOR NOTES
Address for reprint requests and other correspondence: G. Belušič, Dept. of Biology, Biotechnical Faculty, Univ. of Ljubljana, Večna pot 111, Ljubljana 1000, Slovenia (e-mail: gregor.belusic@bf.uni-lj.si).
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Volume 34Issue 2June 2010Pages 90-92
Copyright & PermissionsCopyright © 2010 the American Physiological Society
https://doi.org/10.1152/advan.00015.2010
PubMed20522903
HistoryReceived 28 January 2010
Accepted 20 April 2010
Published online 1 June 2010
Published in print 1 June 2010
Keywordsplethysmography
piezoelectric sensor
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American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
American Journal of Physiology-Renal Physiology
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How We Teach
Explicit constructivism: a missing link in ineffective lectures?
E. S. Prakash
01 JUN 2010https://doi.org/10.1152/advan.00025.2010
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Abstract
This study tested the possibility that interactive lectures explicitly based on activating learners' prior knowledge and driven by a series of logical questions might enhance the effectiveness of lectures. A class of 54 students doing the respiratory system course in the second year of the Bachelor of Medicine and Bachelor of Surgery program in my university was randomized to two groups to receive one of two types of lectures, "typical" lectures (n = 28, 18 women and 10 men) or "constructivist" lectures (n = 26, 19 women and 7 men), on the same topic: the regulation of respiration. Student pretest scores in the two groups were comparable (P > 0.1). Students that received the constructivist lectures did much better in the posttest conducted immediately after the lectures (6.8 ± 3.4 for constructivist lectures vs. 4.2 ± 2.3 for typical lectures, means ± SD, P = 0.004). Although both types of lectures were well received, students that received the constructivist lectures appeared to have been more satisfied with their learning experience. However, on a posttest conducted 4 mo later, scores obtained by students in the two groups were not any different (6.9 ± 3 for constructivist lectures vs. 6.9 ± 3.7 for typical lectures, P = 0.94). This study adds to the increasing body of evidence that there is a case for the use of interactive lectures that make the construction of knowledge and understanding explicit, easy, and enjoyable to learners.
lectures in which the outstanding feature is the transmission of a body of knowledge from the teacher to the student without much dialogue between the two and without continual assessment of the outcome of this effort are commonly believed to be a less effective approach to teaching and learning (1). Despite the increasing adoption of strategies such as problem-based learning and a variety of other learner-centered strategies that have been shown to promote active and meaningful learning (see Ref. 10 and references therein), the lecture format remains and is likely to persist as an important teaching-learning method in higher education. Thus, factors that affect the effectiveness of lectures have been the subject of much interest and research (e.g., Refs. 3–5 and 11). Indeed, it is widely acknowledged that learning new information is likely to be effective when prior knowledge is activated (2, 4, 8–10) and learning is driven systematically by a series of logical questions that engage learners. This study was designed to test if such an approach to lecturing (henceforth called the "constructivist" lecture) would augment the effectiveness of lectures when it is undertaken explicitly.
METHODS
A class of 54 students doing the respiratory system course in the second year of the Bachelor of Medicine and Bachelor of Surgery (MBBS) program of the Faculty of Medicine of Asian Institute of Medicine, Science and Technology (AIMST) University was randomized to two groups to receive one of two types of a block of three lectures on the regulation of respiration: "typical" lectures (n = 28, 18 women and 10 men) or constructivist lectures (n = 26, 19 women and 7 men). I told students that I was comparing two types of lectures but they did not know which type of lecture they were receiving. I requested them not to exchange handwritten notes until the block of lectures was completed, but I could not verify if they exchanged information and, if so, to what extent. That the two groups were comparable at baseline was ascertained with a pretest that contained some questions from previous lectures on respiration. The pretest scores of the two groups were comparable (P > 0.1; Table 1).
Enlarge tableTable 1. Student scores on the pretest, first posttest, and second posttest
Enlarge table
What happened in the lectures?
I prepared well for both types of lectures and delivered both of them enthusiastically. I really regret not having planned in advance to videotape these sessions, as this would have helped the reader make an independent assessment of what happened in the lectures, including the nature and extent of student participation in each type of lecture. However, I am sure that the reader can make out the fundamental difference between the typical lectures and the constructivist approach from the lecture slides [see Supplemental Material, Supplement 1 (typical lectures) and Supplement 2 (constructivist lectures)]. We don't yet have the benefit of personal response systems to augment interactions during lectures, so my students did not have them in this study. The typical lectures were, for the most part, didactic; however, interactions were encouraged and did occur. Learners' construction of knowledge was assumed, and questions that promoted interactions between students and me were much less frequent. However, in the constructivist lectures, we progressed through the topic using a series of logical questions that led at least some of the students to respond. This provided me with the opportunity to assess the participants' "mental models" and clarify misconceptions as well as appreciate thinking along the right lines. I wish to add that I felt excited that we were together constructing a body of fundamental knowledge and understanding on the regulation of respiration (see also the student comments on the constructivist lectures in Table 4). Periodically, I explicitly summarized the collective understanding that I thought emerged in the classroom before passing on to the next subtopic. One can readily see from the slides that the constructivist approach featured considerable teleological speculation; however, these were developed into hypotheses, and there were questions on how such a hypothesis could be tested, what the principal observations of the resulting experiments were, and what they indicated about physiological mechanisms.
Prespecified end points.
The effectiveness of lectures was assessed on the basis of student scores on a posttest (see Supplemental Material, appendix 1: posttest) conducted immediately after the conclusion of the last lecture. The posttest questions were written by me to assess student understanding of some of the core concepts covered by these lectures, and it was designed to be nearly fully objectively scorable. Additionally, students were requested to provide anonymous feedback of their perceptions on certain aspects of the lectures (see Supplemental Material, appendix 2: feedback form) they received. Free text comments were also invited. To determine if there were differences between the two groups in the long term, the same posttest was also administered 4 mo after these lectures were given. However, students did not know that they were going to be given the same posttest 4 mo later. Students consented to participate in this research, and the Faculty of Medicine Research and Ethics Committee of AIMST University approved this protocol.
RESULTS
While I completed a block of three typical lectures in a total of ∼90 min (∼30 min each), to complete a block of three constructivist lectures took ∼30 min more. Students that received the constructivist lectures did much better in the posttest conducted immediately after the lectures (6.8 ± 3.4 for in the constructivist lectures vs. 4.2 ± 2.3 for the typical lectures, means ± SD, P = 0.004 by Mann-Whitney U-test). Please note that in Table 1 median rather than mean scores are provided with 95% confidence intervals of the mean because the distribution of scores was apparently non-Gaussian. Although both types of lectures were well received, students that received the constructivist lectures had greater overall satisfaction with their learning experience (see students ratings in Tables 2 and 3). However, on a posttest conducted 4 mo later, scores obtained by students in the two groups were not any different (6.9 ± 3 for the constructivist lectures vs. 6.9 ± 3.7 for the typical lectures, means ± SD, P = 0.94, not significant]. It is worth noting that between the first and the second posttest, the median score increased significantly (P < 0.01) in the group that received the typical lectures, whereas the score of students that received the constructivist lectures remained stable (P = 0.9). All tests were scored by E. S. Prakash (the author), who was blinded to the type of lecture that the students received.
Enlarge tableTable 2. Student ratings of the typical lecture
Enlarge table
Enlarge tableTable 3. Student ratings of the constructivist lectures
Enlarge table
DISCUSSION
Although the outcome on the second posttest did not differ significantly between the two groups, the fact that students who participated in the constructivist lectures did much better on the posttest immediately after the lectures suggests that an explicitly constructivist approach to lecturing does indeed better facilitate learning with understanding. In contrast, students that received typical lectures took longer to get even, in terms of scores on the posttest, with those that received the constructivist lectures. More importantly, from the comments of students who participated in the constructivist lectures, one can see that they found the constructivist lectures helpful. The results support the idea that explicit constructivism is a key principle for augmenting the effectiveness of lectures. These observations are not new, and the reader is referred to a review of research on constructivist-based strategies for large lectures by Geer and Rudge (4). However, I believe that for medical physiology educators who continue to use a predominantly didactic approach for lecturing or for those whose seek to facilitate learning with understanding but are constrained to use lectures as a major teaching method, the narrated experience and the accompanying supplement (see Supplemental Material, Constructivist lectures on the regulation of respiration) may provide a useful working example for planning and incorporating aspects of constructivist philosophy into lectures.
Constructivist learning environments and experiences have been extensively characterized (e.g., see Refs. 2, 4, 7, 10, 11, and 13). I wish to note that the constructivist lectures described in this study encompassed the following core features that stem from constructivist philosophy: consolidating prior knowledge; engaging learners with a series of logical questions that invite them to activate prior knowledge; negotiating the scientific method (question-predict-observe-explain), thereby providing a basis for future independent inquiry into the content and concepts brought out in the lectures; the explicit nature of the attempt to construct knowledge and understanding; and dialogue between the facilitator and participating students until flawed conceptions were refined. Finally, there was an opportunity for learners to obtain a sense of discovery, greater engagement in the learning process (as students comments suggest; Table 4), and ownership of learning. For example, when I asked the class the informal question "Where would you like to have these receptors? On the arterial or venous side of the circulation?," a large number of students responded by saying that they would expect them to be on the arterial side of the circulation because that would allow the chemoreceptors to verify whether the pH, Po2, and Pco2 of blood supplied to metabolizing tissues were optimal or not. And I replied, "You are absolutely right! Indeed, the chemoreceptors that sense arterial pH and Po2 are located in the aortic and carotid bodies, on the arterial side of the circulation."
Enlarge tableTable 4. Selected student comments (each comment is from a different student)
Enlarge table
Limitations.
There are several limitations that would potentially confound the interpretation of results. First, the same teacher (E. S. Prakash, the author) delivered both the typical and constructivist lectures. I thought that this would confound the outcomes less than if I were to have two different lecturers deliver the typical and constructivist lectures. The latter approach would inevitably have introduced a bias attributable to differences in the teaching abilities and philosophies of the two teachers. I wrote the posttest questions; however, readers can assess the validity of these test items. In the context of the stated hypothesis, one may wonder if I could have been as enthusiastic about delivering the typical lectures. In this regard, I regret not having videotaped these sessions. As noted earlier, videotaping these sessions would have additionally helped to document the differences in the nature and extent of student participation in the two types of lectures. I acknowledge that some of the concepts presented in these lectures, particularly in reference to the neural basis for the regulation of respiration, are oversimplified and/or hypothetical. This was intentional; indeed, the central neural substrates for respiratory control continue to be a subject of intense experimental research. The results of this study were obtained with a rather convenient class size of 25–28 students, and I don't think it correct to readily extrapolate this to much larger classes.
Practice issues.
Many practical implications of a constructivist philosophy of teaching have been suggested (2, 4, 6, 8–10, 13). I wish to highlight some issues in light of this experience. First, and quite obviously, constructivist teaching-learning experiences consume more time than instructive approaches because of the amount of interactions that may be required before the facilitator is convinced that a satisfactory conceptual model has emerged in the minds of learners. Furthermore, the level at which the lectures are pitched should, by definition, take into consideration prior knowledge of low achievers in that class of students so that the teaching-learning experience could be expected to benefit virtually every student in the class. For example, in this study, my audience was undergraduate students in the second year of the medical program, and I thought it appropriate to start building into the neural and chemical regulation of respiration by first asking a teleological question: Why we needed to breathe at all?
Third, a point-by-point comparison of the two PowerPoint files (typical vs. constructivist lectures) will indicate that the constructivist lectures were not intended and prepared to deliver all the facts that were delivered in the typical lectures. Rather, these lectures (whether typical or constructivist) were prepared and delivered as a means to facilitate the attainment of prespecified intended learning outcomes. The fact that students who received typical (more comprehensive) lectures did no better than those who received constructivist lectures in the second posttest suggests that where the intended outcome is learning with understanding, covering more content isn't necessarily better. The issue of whether lectures (or comparable teaching-learning methods) in higher education should primarily seek to cover content has rightly been the point of much discussion (1, 12, 14). Undoubtedly, the most significant effect the narrated experience has had on me as a medical physiology educator is drive me into more critically examining than ever before what I eventually want my students to be able to do (with what is learned) at the end of each lecture, a particular course, and then upon graduation from the MBBS program as a doctor and, in turn, use this renewed vision of intended learning outcomes to temper approaches to facilitating learning as well as the assessment of learning.
Fourth, many topics in physiology, the regulation of metabolism, and pathophysiology naturally lend to constructivist approaches. Finally, and perhaps most important, irrespective of whether a teaching-learning experience is designed to be "instructivist" or "constructivist" or something in between, the truth is that for learning to occur with understanding, the learner has to ultimately construct his/her own mental models of the external world (1, 8–10, 13). This implies that the usefulness of knowledge of constructivist approaches is not limited to designing constructivist teaching-learning experiences; rather, it is fundamental to understanding "meaningful learning."
In conclusion, despite the limitations of this pilot study, the results indicate that it is possible to incorporate cardinal features of constructivism into designing and delivering lectures that make the construction of knowledge and understanding explicit, easy, and enjoyable to learners. I am certainly much more motivated now than before to take efforts toward using an explicitly constructivist approach to preparing and delivering lectures wherever possible. However, I believe the overall impact of this effort on student learning will be substantial only if entire courses (or major portions of it) are designed and delivered based on constructivist principles. More importantly, a substantial fraction of assessment of learning should focus on assessing if meaningful learning has occurred rather than test retention of the facts per se. This can then be eventually expected to foster a positive change in the minds of students who mistakenly think that learning is simply acquiring new information without necessarily understanding the potential or actual utility of learned knowledge. One surrogate of impact of such an approach that merits research is whether students would adopt a constructivist approach to learning during their own study time, in preference to rote learning.
DISCLOSURES
No conflicts of interest, financial or otherwise, are declared by the author(s).
ACKNOWLEDGMENTS
Results of this work were presented at the 5th Asia-Pacific Medical Education Conference at the National University of Singapore in 2008.
AUTHOR NOTES
Address for reprint requests and other correspondence: E. S. Prakash, Dept. of Physiology, Faculty of Medicine, AIMST Univ., Bedong 08100, Kedah Darul Aman, Malaysia (e-mail: dresprakash@gmail.com).
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Volume 34Issue 2June 2010Pages 93-96
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Copyright & PermissionsCopyright © 2010 the American Physiological Society
https://doi.org/10.1152/advan.00025.2010
PubMed20522904
HistoryReceived 23 February 2010
Accepted 24 April 2010
Published online 1 June 2010
Published in print 1 June 2010
Keywordsmeaningful learning
active learning
interactive lecture
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Teaching in the Laboratory
Outcome assessment of a computer-animated model for learning about the regulation of glomerular filtration rate
Jody L. Gookin,
Dan McWhorter,
Shelly Vaden, and
Lysa Posner
01 JUN 2010https://doi.org/10.1152/advan.00012.2010
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Abstract
The regulation of the glomerular filtration rate (GFR) is a particularly important and challenging concept for students to integrate into a memorable framework for building further knowledge and solving clinical problems. In this study, 76 first-year veterinary students and 19 veterinarians in clinical specialty training (house officers) participated in separate online exercises to evaluate the use of a computer-animated model of GFR regulation (www.aamc.org/mededportal) on learning outcome. Students were randomly allocated to study either the animated model or written materials before completion of a 10-question multiple-choice quiz. House officers completed a 35-question test before and after study of the animated model. Both groups completed a survey about the learning exercise. The ability of the model to enhance learning was demonstrated by a significant improvement (P < 0.001) in the test performance of house officers after studying the model. The model performed similarly to written materials alone in affecting the subsequent quiz performance of the students. The majority of students and house officers agreed or strongly agreed that the animated model was easy to understand, improved their knowledge and appreciation of the importance of GFR regulation, and that they would recommend the model to peers. Most students [63 of 76 students (83%)] responded that they would prefer the use of the animated model alone over the study of written materials but acknowledged that a combination of hardcopy written notes and the animated model would be ideal. A greater applicability of the model to more advanced students and an introduction in a didactic setting before individual study were suggested by the house officers. The results of this study suggest that the animated model is a useful, effective, and well-received tool for learning and creating a visual memory of the regulatory mechanisms of GFR.
the kidney is one of the most complex internal organs. This is due, in large part, to the multiple and integrated functions of the kidneys and their highly dynamic regulation by a variety of neurohormonal and hemodynamic inputs. Accordingly, it is challenging to teach renal physiology in a manner that promotes an integrated concept of dynamic kidney function. One of the primary functions of the kidneys is to remove water-soluble waste products from the blood and to precisely and rapidly control the volume and composition of the extracellular fluid.
These functions depend on the exquisite regulation of plasma filtration by ∼2 million specialized capillary tufts within the kidneys called glomeruli. The glomerular filtration rate (GFR) is largely dependent on intraglomerular hydrostatic pressure, which is governed by the control of afferent and efferent arteriolar resistance. In turn, the control of afferent and efferent arteriolar resistance is regulated by dynamic myogenic (autoregulation), neurocrine, paracrine (tubuloglomerular feedback), and endocrine (ANG II, endothelin, atrial natriuretic peptide, and arginine vasopressin) stimuli, which each have unique and overlapping sensory mechanisms. Multiple diseases (e.g., heart failure, renal failure, and systemic hypertension) and therapeutic drugs [e.g., inhibitors of angiotensin-converting enzyme (ACE), ANG II receptors, and cyclooxygenase] converge on these pathways to impact the GFR in clinically significant ways. Consequently, the regulation of GFR is a particularly important and challenging concept for students to integrate into a memorable framework for building further knowledge and solving clinical problems.
In the present study, we investigated use of an animated model for teaching veterinary medical students and veterinarians in specialty training about the regulation of GFR. We hypothesized that students would prefer the use of the animated model over the use of written materials alone for learning about GFR regulation and that a significant increase in knowledge would be obtained by the use of the model.
MATERIALS AND METHODS
Animated Model of GFR Regulation
The computer animated model (2) was designed to provide an interactive platform for learning the regulatory mechanisms of GFR (Fig. 1). The educational objectives of the model were to demonstrate 1) the effect of afferent and efferent arteriolar resistance on renal blood flow, glomerular hydrostatic pressure, GFR, filtration fraction, and tubular flow; 2) autoregulatory and tubuloglomerular feedback mechanisms for the regulation of GFR by changes in afferent arteriolar resistance; and 3) the effect of the renin-angiotensin-aldosterone system on the regulation of GFR in response to systemic hypotension. The model is capable of animating the direct effect of afferent and efferent arteriolar resistance and systemic blood pressure on renal blood flow, glomerular hydrostatic pressure, GFR, filtration fraction, and tubular flow. In the program, afferent and efferent arteriolar resistance (increase or decrease) and systemic blood pressure (180-, 80-, or <60-mmHg positions) are user controlled by moving designated sliders. In addition to animating the uncompensated effects of changes in afferent and efferent arteriolar resistance or systemic blood pressure, the model animates renal autoregulatory and tubuloglomerular feedback control of afferent arteriolar resistance and the effect of renin-angiotensin-aldosterone activation on the control of GFR. Selection of a "show notes" feature provides a written explanation of the observed physiological responses. The model is accessible at www.aamc.org/mededportal. This website is available to all users provided that they agree to the MedEdPORTAL Privacy Policy, register as a new user, and install Shockwave Player software to run the animation.
Fig. 1.Online appearance of the animated model of regulation of the glomerular filtration rate (GFR). Learning modules are selected in the top left corner of the screen. The control of afferent and efferent arteriolar tone and systemic blood pressure are controlled using designated sliders. The effect of each stimulus is depicted categorically in the bottom left screen and animated by the program. Anatomic labels and text can be shown or hidden under the discretion of the user.
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Recruitment of Study Participants
Veterinary students.
All students enrolled in the first year of the veterinary medical curriculum (n = 78) were invited to participate in the study. Students were currently enrolled in a semester-long course in veterinary physiology. An invitation was made on the first day of class instruction in renal physiology and then followed up by a same-day e-mail solicitation. Students were informed that participation in the study would entail their accessing, via the internet, a learning exercise on the regulation of GFR. After studying the materials, they would be directed to take an online closed-book quiz. Subsequently, they would be directed to an alternative method of learning the same material and then directed to complete an online survey. Study was required to be completed within a 2-wk period, during which didactic instruction in renal physiology was ongoing. As an incentive to participate in the study, students were awarded 5 points toward any points lost on an upcoming midterm examination in renal physiology. The midterm examination was worth a total of 120 points (or 23.5%) of the total course grade. As an alternative to participating in the study, equal credit could be obtained by writing a 5-page essay addressing the mechanisms for the regulation of GFR and the rationale for the use of ACE inhibitors to treat glomerular proteinuria.
House officers.
All graduate veterinarians currently engaged in advanced clinical training (internship or residency program) in the veterinary teaching hospital (n = 77) were invited by e-mail solicitation to participate in the study. House officers were informed that participation in the study would entail their accessing, via the internet, a challenging pretest on glomerular physiology. After completing the test in a closed-book fashion, they would be directed to an animated learning exercise on the regulation of GFR. After studying the model, they would be directed to a closed-book posttest on glomerular physiology followed by a direct link to an online survey. House officers were instructed to complete the study in one sitting and within a 3-wk time period. Incentives were not provided to participate in the study other than a statement that the model was likely to contain material relevant to board certification examinations. Informed consent was provided by participating students and house officers, and the study was approved by the Institutional Review Board of North Carolina State University.
Study Design
Veterinary students.
Students were randomly allocated to one of two learning methods with the use of a random integer generator (www.random.org). Even-numbered students were sent an e-mail containing a URL address enabling access to a secure internal webpage containing the animated model of GFR (ANIM group). Odd-numbered students were sent an e-mail containing a URL address enabling access to a secure internal webpage containing written materials describing the regulation of GFR and a still image of the glomerulus (TXT group). The written material and still image were excerpted verbatim from the animated model. Both groups of students were instructed to spend as much time as they needed to study the material. At the bottom of the webpage, students were instructed to select a link that directed them to a 10-question multiple-choice quiz (appendix a). At the termination of the quiz, students were instructed to select a link that directed them to a secure internal webpage containing the alternative learning materials. Accordingly, students in the ANIM group were directed to access the written materials and students in the TXT group were directed to access the animated model. Students were shown the alternative learning materials so that their preference could be queried in the final survey. At the bottom of the alternative learning materials webpage, all students were instructed to select a link that directed them to an eight-question survey about the learning exercise (appendix b).
House officers.
All house officers expressing an interest in participating in the study were sent an e-mail containing a URL address enabling access to a secure internal webpage containing a 35-question pretest (appendix c). At the bottom of the webpage, house officers were instructed to select a link that directed them to the animated model of regulation of GFR. House officers were not randomized to the study of written materials because we anticipated a smaller sample size of house officers willing to participate in the study compared with veterinary students. Upon exiting the animated model, they were instructed to select a link that directed them to a posttest of identical question composition as the pretest. Finally, at the bottom of this webpage, all house officers were instructed to select a link that directed them to a 14-question survey about the animated model (appendix d).
Statistical Analysis
All data were analyzed for normality (Kolmogorov-Smirnov) and variance (Levene median) using a statistical software package and tested for significance using parametric or nonparametric tests as appropriate (SigmaStat, Jandel Scientific). The proportion of students responding correctly to each test or survey item was compared using a z-test. Pre- and posttest result scores were compared using a Student's paired t-test. Statistical significance was assigned to P values of <0.05.
RESULTS
Participant Demographics
Veterinary students.
Seventy-six first-year veterinary medical students participated in the study, including 37 of 37 students assigned to the ANIM group and 39 of 41 students assigned to the TXT group. Two students elected not to participate, both of which would have been assigned, based on a priori allocation, to the TXT group. No students elected to prepare an essay examination as an alternative means to obtain equivalent credit.
House officers.
Twenty-nine house officers expressed an interest in participating, of which 19 completed the study. These house officers included 5 interns and 13 residents, the latter of which were pursuing board certification in small animal internal medicine (6), critical care (2), large-animal internal medicine (2), neurology, anesthesia, and clinical pathology. The status of one house officer was unspecified.
Influence of the Model on Learning Outcome
Veterinary students.
After studying their assigned primary learning material, students in the ANIM and TXT groups achieved similar item-specific and total scores on the subsequent quiz (ANIM group: mean 7.2 points, range 3–10 points; and TXT group: mean 7.4 points, range 2–10 points).
House officers.
After studying the animated model, house officers demonstrated a significant improvement in test performance [pretest mean: 23 of 35 (65%) points, range 13–31; and posttest mean: 32 of 35 (92%) points, range 29–34, P < 0.001 by Student's paired t-test]. The improved test performance could be attributed to a significant improvement in the response to 14 of 35 (40%) specific test questions (Fig. 2). Examination subject areas in which house officers initially performed poorly and demonstrated significant improvement after study of the model included the differential role of afferent and efferent arteriolar resistance on filtration fraction, the anatomic location of juxtaglomerular and macula densa cells, understanding of myogenic and tubuloglomerular feedback control of GFR, identification of the specific stimuli responsible for stimulating renin release, and the effect of endogenous prostaglandins on afferent arteriolar resistance.
Fig. 2.Percentage of house officers (n = 19) responding correctly to each of 35 questions administered as a closed-book examination before (pretest) and after (posttest) independent study of the animated model of GFR regulation. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001 (by z-test).
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General Impressions of the Animated Model
The majority of students agreed or strongly agreed that the animated model was easy to understand, improved their knowledge and appreciation of the importance of GFR regulation, and that they would recommend the model to other students. Less than enthusiastic responses were obtained from ∼20% of students. Compared with the veterinary students, house officers were significantly more likely to strongly agree that the animated model improved their knowledge and appreciation of the importance of GFR regulation and that they would recommend the model for use by other house officers (Fig. 3).
Fig. 3.Percentage of veterinary students and house officers responding to Likert scale-type questions pertaining to the animated model of GFR regulation. *P ≤ 0.05; **P ≤ 0.01 (by z-test).
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Preferences for Learning Method
Sixty-three of seventy-six (83%) veterinary students responded that they would prefer the use of the animated model over the study of written materials alone. Students preferring the use of the animated model voluntarily identified themselves as visual learners. The reasons provided for their choice of the animated model included the ability to test their knowledge by predicting the regulatory responses before executing the animation, the benefit of forming a lasting visual memory, and the enjoyment of active participation in the learning process. These students liked the combination of written information and animation in a single resource. Most commented that the written descriptions included in the program were essential to a full understanding of the material. In contrast, 13 of 76 students (17%) responded that they would prefer the use of the written materials alone if only one of the two learning methods was available. These students found the written materials to be a concise, time efficient, and orderly way in which to learn the subject content. In contrast, the use of the animated model alone they found disorienting, time consuming to master the use of, and lacking direction in how to navigate through the program. Most of these students volunteered that the animated model would be helpful to their learning and make better sense if the written materials were also provided and studied first. There were no statistically significant differences in the preference of learning material based on whether students were initially randomized to study the written material rather than the animated model.
While house officers were not provided with alternative study materials or asked about their learning preferences, attributes that they liked about the model included the responsiveness of the program to user input and the ability of the user to manipulate individual variables and control the pace and repetition of the program. They appreciated that the model could appeal to both visual and reading learning styles and provided both basic and clinically applicable knowledge. Dislikes about the model were that it was graphically "busy" and somewhat difficult to confidently identify all of the responses being animated simultaneously.
House Officer Opinions on the Target Audience
Most house officers (66%) felt that the model would be best used as a learning tool if introduced in a didactic setting and then made available for individual study. Lesser numbers indicated the best use of the model as an independent study aid (28%) or visual aid during didactic lecturing on glomerular physiology (5%). It was the opinion of the house officers that use of the model would most greatly benefit interns and residents (percent responding very beneficial: 89%) followed by continuing education presentations (83%) and senior medical students (e.g., veterinary, medical, nursing, and pharmacy, 80%). Less enthusiasm was provided for use of the model for learning by first-year veterinary students (50%).
Recommendations for Improvements to the Animated Model
Both students and house officers provided similar recommendations for improvement to the model. The program text was considered by many to be too small, and its location interfered with the visualization of animation at the bottom of the screen. In addition to increasing the font size and relocating the text box, users suggested that a feature enabling the text to be advanced in sequence with the animation would be desirable. Additionally, the ability to pause or advance the animation stepwise rather than continuously was sought by several users. Many were unable to discern a change in the animation of tubular flow or arteriolar contraction/relaxation. Some suggestions to improve this included the use of superimposed arrows or highlighting regions of interest to draw attention to the timing, location, and magnitude of these events.
Extended features that the users suggested would improve the program included animations of the effect of drugs (cyclooxygenase, ACE, and Ca2+ channel inhibitors) on GFR, an audio narration describing the animated responses, and written instructions on how to navigate through the program. A number of users commented that they would like to see a similar program depicting Na+ and water transport by the nephron.
DISCUSSION
There was no evidence that independent study of the animated model improved student test performance compared with the use of text alone as the primary study material. This could reflect a similar acquisition of knowledge or, alternatively, an inability of the quiz to differentiate the depth of differences in understanding between the two groups. The significance of these results compared with similar studies is uncertain because only a handful of controlled studies, with conflicting results, have ever been undertaken to ascertain the effectiveness of animations in medical education (7). However, students volunteered that the formation of a visual memory of GFR regulation was a key impact of the model. It would be compelling to investigate whether these visual memories provide a superior platform for later recall, advancement, and application of knowledge. We could find few published studies directly evaluating the effect of animation on memory retention. In one of these studies (6), students retained significantly more information 21 days after studying an unnarrated animation compared with the use of a static graphic.
While veterinary students studying either the animated model or written materials performed similarly on a subsequent test of their knowledge of GFR regulation, our use of a pretest and posttest with house officers demonstrated a remarkable improvement in learning after use of the animated model. Although house officers were not aware that the pretest and posttest questions were identical, it is possible that the pretest increased an awareness of deficiencies in the knowledge base that enhanced the learning potential of the model. Likewise, preexisting knowledge of a posttest may have contributed to the similar performance by the veterinary students regardless of learning material. Our use of a pretest additionally identified specific topics where background knowledge of glomerular physiology was deficient. Lack of understanding of the influence of arteriolar resistance on filtration fraction, for example, was not surprising; however, the inability to identify the specific mechanisms responsible for mediating renin release was unexpected and suggests that greater emphasis on this topic in the veterinary curriculum may be warranted.
The majority of first-year veterinary medical students and house officers participating in this learning exercise agreed or strongly agreed that the animated model was easy to understand, improved their knowledge and appreciation of the importance of GFR regulation, and that they would recommend the model to others in their peer group. If given a choice, most veterinary students would prefer the use of the animated model rather than written materials alone for learning about GFR regulation. Most acknowledged, however, that a combination of hardcopy written notes and the animated model would be ideal. This finding agrees with recent studies (1, 3) identifying that most premedical students [55 of 80 (69%) students] and first-year medical students [166 of 250 (76%) students] have multimodal learning preferences.
Several observations from this study suggest that the animated model may be best suited for use by house officers or students in the final year rather than first year of the veterinary medical curriculum. House officers responded more favorably to questions pertaining to the usefulness of the model and whether they would recommend it for use by others. The greater appeal of the model to house officers may reflect a stronger working knowledge of renal physiology, cultivated interest in the physiological basis of renal disease, or perceived relevance of the subject to certifying examinations. Several house officers identified first-year veterinary students as a group that would be unlikely to benefit from use of the model, perhaps because they perceived the model and subject material to be challenging for students with a minimal knowledge of renal physiology. There is some evidence to suggest that the learner's level of knowledge or expertise in the subject area will impact the outcome of learning using animation (4, 5, 7). Novice learners may not possess the metacognitive skills or prior knowledge to correctly extract and process information from the animation, particularly if it contains complex content or requires attention to simultaneous screen events. This may explain why some veterinary students found the model disorienting and somewhat difficult to confidently identify responses that were animated simultaneously. In contrast to animation, static images allow more novice learners to review the information for as long as they need to achieve understanding. Evidence has suggested that breaking animations into smaller segments reduces extraneous cognitive load and that control of the pace of animation improves learning efficiency (7).
The results of this study suggest that the animated model is a useful, effective, and well-received tool for learning and creating a visual memory of the regulatory mechanisms of GFR. The program may be best suited for students already having some background knowledge of renal physiology and should be accompanied by a set of hardcopy notes or text on glomerular physiology. An introduction to the program in class or use of the accompanying instructor's guide (at www.aamc.org/mededportal) is likely to facilitate use of the model as an independent learning tool.
GRANTS
Development of the animated model of regulation of GFR was made possible by a competitive grant in teaching innovation from the office of the Associate Dean of Student Affairs, College of Veterinary Medicine, North Carolina State University.
DISCLOSURES
No conflicts of interest, financial or otherwise, are declared by the author(s).
APPENDIX A: MULTIPLE-CHOICE QUIZ ADMINISTERED TO THE VETERINARY STUDENTS
Without using the instructional materials provided, please answer the following multiple-choice questions pertaining to the regulation of GFR. Please give your best effort to your answers; however, your responses will not be used in determining your grade.
Which one of the following is normally filtered by the renal glomeruli into Bowman's space:
Red blood cells
Plasma fluid
Albumin and globulins
White blood cells
Which one of the following is the best definition of GFR:
The volume of plasma that is filtered by the renal glomeruli over a given time
The fraction of plasma that is filtered by the glomeruli over a given time
The volume of urine produced by the kidneys over a given time
The volume of blood that is flowing into the afferent arterioles over a given time
Which one of the following is under the direct control of both afferent and efferent arteriolar tone:
Colloid osmotic pressure within the glomerulus
Glomerular filtration coefficient
Filtration fraction
Hydrostatic pressure within the glomerulus
Constriction of the afferent arteriole results in which one of the following:
Decrease in glomerular hydrostatic pressure
Decrease in the filtration fraction
Increase in GFR
Increase in tubular flow rate
Mild to moderate constriction of the efferent arteriole results in which one of the following:
Decrease in glomerular hydrostatic pressure
Increase in the filtration fraction
Decrease in GFR
Decrease in tubular flow rate
How does the kidney respond to a direct increase in blood pressure and GFR?
Contraction of the afferent arteriole
Contraction of the efferent arteriole
Relaxation of the afferent arteriole
Relaxation of the efferent arteriole
How does the kidney respond to a mild decrease in mean arterial blood pressure (∼80 mmHg) and GFR?
Contraction of the afferent arteriole
Contraction of the efferent arteriole
Relaxation of the afferent arteriole
Relaxation of the efferent arteriole
When blood pressure drops precipitously low (<60 mmHg), which one of the following mediators is NOT responsible for stimulating the release of renin from the juxtaglomerular cells?
ANG II
Decreased flow rate in the distal renal tubule
Decreased stretch of the afferent arteriole
Secretion of norepinephrine by renal nerves
When mean blood pressure drops precipitously low (<60 mmHg), which one of the following mediators prevents the afferent arteriole from constricting in response to the actions of norepinephrine?
Prostaglandins
ATP
Renin
ANG II
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Teaching in the Laboratory
A housefly sensory-motor integration laboratory
Edwin R. Griff, and
Thomas C. Kane†
01 JUN 2010https://doi.org/10.1152/advan.00068.2009
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Abstract
Insects have many interesting behaviors that can be observed in an introductory biology laboratory setting. In the present article, we describe several reflexes using the housefly Musca domestica that can be used to introduce students to sensory and motor responses and encourage them to think about the underlying neural circuits and integration of sensory information that mediate the behaviors.
biology students in introductory courses have an innate interest in animal behavior. Reflexes are relatively simple behaviors that often are used in these courses to illustrate the neural connections and underlying physiological mechanisms linking the sensory stimulus to the motor response. One would hope to find a wide range of laboratory exercises that explore various animal reflexes. However, introductory biology laboratory manuals either do not include experiments to investigate sensory-motor integration (e.g., Refs. 7, 20, and 31) or rely solely on human-based experiments, most commonly the patellar tendon (knee-jerk) reflex and the pupillary reflex (e.g., Refs. 13, 14, 24, and 27). These human reflexes are easy to demonstrate, but the patellar tendon reflex is quite unusual in being monosynaptic, and the circuits underlying the pupillary reflex are very complex, involving neural circuits in several distinct nuclei in the brain. In most laboratory manuals, these human reflex circuits are described as excitatory and no examples of inhibitory reflexes are given. Furthermore, the sensory organs for these human reflexes (the muscle spindle and retina, respectively) are quite complex; most laboratory manuals do not describe or discuss this complexity. This article presents alternative experiments that can be used in conjunction with human reflex exercises or in place of them.
The laboratory exercises detailed below let students observe relatively simple behaviors, and they encourage students to hypothesize what neural circuits underlie them, thereby integrating organismal, organ system, and cellular levels. These exercises focus on the housefly, an organism that is easy to obtain and maintain even for large classes (see materials and methods). Working with a small invertebrate adds a comparative perspective, provides opportunities for experimentation in an inquiry-based learning environment, and presents novel and intriguing anatomic structures. Excitatory and inhibitory responses are observed in the same organism. The exercises below could complement a nervous system, sensory, behavior, or human reflex laboratory in an introductory biology course. The exercises illustrate general mechanisms underlying sensory motor integration. In addition, this article provides detailed methods and extensive background and references on the studied reflexes so that these exercises can more easily be incorporated into a variety of courses at several levels.
Demonstrating sensory-motor integration in an invertebrate reinforces the important evolutionary principles that all extant organisms have equally long evolutionary histories and use almost identical mechanisms. The presence of taste receptors on a fly's feet, a proboscis for feeding and drinking, and a vestigial wing called the haltere, which is used for flight stability, also demonstrate unique adaptations in insects that will arouse interest and stimulate curiosity. Houseflies are common, but most students have never looked at them carefully; seeing the compound eye, mouthparts, and sensory hairs at relatively high magnification under a dissection microscope can be an amazing experience. Comparing reflexes and sensory-motor integration in humans and flies should also help students accept the importance of using model systems such the fruit fly Drosophila melanogaster, the sea anemone Aplysia californica, or the nematode Caenorabditis elegans to study general principles of animal physiology.
The overall goal is to understand the anatomy and physiology of a reflex by analyzing two examples: the proboscis extension and tarsal reflexes. After completing the exercises, students will be able to 1) identify fly structures such as the proboscis, tarsi, wings and halteres; 2) determine appropriate sensory stimuli for each reflex; 3) hypothesize specific sensory structures and receptors that are required for each reflex; 4) describe the motor responses generated in each reflex; and 5) propose neural circuits that could mediate the reflexes. The objectives can be extended to include the specific structures and muscle groups that participate in the motor outputs.
In my department, these activities were used in the laboratory part of an introductory biology course taught in the freshman year and intended for Biology majors. There were ∼500 students in this course with laboratory sections of ∼25 students each. The exercises were part of the sensory physiology exercise that also included mapping of sensory receptors on the skin, demonstration of the pupillary reflex, and exercises measuring reaction times under different conditions. If students have already studied some neurophysiology and/or muscle physiology, these reflex examples will reinforce the physiological concepts and apply them to simple behaviors. If not, these reflex laboratories can be used to introduce the nervous and muscular systems.
These laboratory activities can be presented in a traditional format, where students follow written procedures and answer written and/or oral questions based on their observations. The exercises can also be used in a more inquiry-based setting, where students are given questions and/or problems and must develop experiments themselves using equipment and supplies that are provided to answer the questions or test the hypotheses. A few specific suggestions are given below with the description of the procedures.
This laboratory examines a proboscis extension reflex and a tarsal reflex of a housefly, Musca domestica (Phylum: Arthropoda; Order: Insecta; Class: Diptera). A reflex is a relatively simple behavior triggered by a sensory stimulus. The sensory stimulus typically excites a sensory neuron that synapses onto one or more interneurons in a ganglion. The interneurons, in turn, synapse onto motor neurons that innervate the muscles involved in the behavior.
Based on our 2-yr experience in teaching digestive physiology at the Osijek Faculty of Food Technology in Osijek, Croatia, this article is an attempt to improve students' understanding of carbohydrate metabolism. The presented material is adapted from a Croatian version prepared for students of food technology attending the Digestive Physiology course in their fourth year, after the completion of chemical and biochemical courses that enabled them to understand carbohydrate terminology and metabolism. Students are also expected to show some knowledge regarding digestive tract function and insulin actions. In case of any doubt, students are encouraged to ask questions.
The text is given to students as reading material for a discussion during seminars on carbohydrate metabolism, usually scheduled for the following week. Students can use their textbooks and other references listed in the material, most of them chosen due to their availability as Web sources. Since <20 students were in both classes, they spontaneously shared duties among them, so all sources were found by at least 1 student, which is an expected behavior for a group of fourth-year students. Nevertheless, they showed interest in this topic, which was directly related to their main interest, food technology. We believe that the same or similar material can be helpful in teaching digestion to students of various biomedical programs.
The goal was to gain a more comprehensive view of this topic through a reinterpretation of sugar-related facts taken from their textbooks. After completing the seminar, the student is expected to be able to compare and contrast the digestion of simple sugars by the gastrointestinal tract and the implications for water balance. The student will interpret the actions of insulin and which foods have the greatest effect on insulin release.
Text for Students
Characteristics of dietary sugars and their roles in body metabolism.
Please use your textbooks and other sources listed in the References.
Sugars in food and beverages.
Human carbohydrate metabolism is determined by the presence of different sugars in our diet (Table 1). Most of the carbohydrate calories we eat come from starch, a polymer of glucose.
Enlarge tableTable 1. Characteristics of dietary sugars compared with their roles in body metabolism
Enlarge table
Sucrose, or "cane sugar" in the United States and "table sugar" in Europe, is another important sugar in the Western diet. It is a disaccharide, as molecules of sucrose are dimers that consist of one glucose molecule and one fructose molecule. Sucrose is produced from sugarcane and sugar beets but is also found in fruits. Lactose is the main disaccharide (glucose + galactose) in milk.
Both glucose and fructose as monomers (monosaccharides) can naturally be found along with sucrose in fruits. These two monosaccharides are the main sugars in honey. An artificial mixture of them is produced from corn starch as high-fructose corn syrup (HFCS), which is used as a soft drink and food sweetener.
Sugar ingestion and osmolarity of the intestinal contents.
Oligosaccharides (sucrose, lactose, maltotriose, etc.) and particularly monosaccharides (glucose, fructose, and galactose) are all osmotically active molecules. From the beginning of the duodenum throughout the rest of the small intestine, normal digestion sustains the osmotic pressure of the intestinal contents equal to the plasma (1), with no sudden changes in the osmolarity of the contents.
Correction of osmolarity starts in the stomach through mixing with the gastric juice, but a combination of fluid secretion and absorption of water and solutes in the small bowel maintains the isotonicity of the intestinal contents. Gastric emptying of hypertonic solutions is slowed via the enterogastric reflex, and this is triggered via osmoreceptors in the duodenum. As food is slowly digested in the small bowel, new osmotically active molecules are continuously liberated from food particles, but some of them are also absorbed, so the additional dilution volume by osmosis often remains limited. Water follows the absorption of osmotically active molecules, and this process maintains the isotonicity of the intestinal contents along the small bowel. Thus, the absorption of salt, various sugars, and other substances (e.g., amino acids and water-soluble vitamins) all help in
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