Do Voluntary Lab-Based Active Learning Sessions Impact Medical Student Knowledge Retention?

Abstract

Background

Despite recent evidence demonstrating the benefits of case-based and active learning strategies in medical education, many medical schools have reduced or entirely eliminated teaching laboratories in medical microbiology courses. The objective of our investigation was to analyze the impact of a voluntary hands-on microbiology laboratory session on students’ knowledge retention and ability to apply the underlying principles to exam questions in our Introduction to Infectious Diseases (IID) course.

Methods

We compared the performance of students participating in the wet labs with those who did not, analyzing scores on exam questions directly related to the concepts presented in the laboratory session and their overall scores on the IID module exam. The voluntary nature of our microbiology lab session provided a unique opportunity to assess its impact on knowledge retention independent of other factors, such as lecture and exam content, etc. Data were collected for 7 academic years and analyzed in aggregate.

Results

Students who attended voluntary lab sessions scored higher on exam questions related to lab exercises than students who did not attend (Mann-Whitney, p = 0.0074). These results support the benefit of reexamining material originally presented during classroom sessions in an active, collaborative learning environment. Course evaluation responses indicted that students valued the opportunity to visually reinforce concepts they had previously read in a textbook or heard in lectures.

Conclusions

At a time when many medical schools are reducing or eliminating hands-on lab sessions in microbiology and other basic sciences, our results highlight the benefits of this teaching strategy. The laboratory session provided an opportunity for students to revisit concepts initially presented in the traditional classroom setting and to actively engage in applying these concepts to case-based scenarios. The improved educational outcomes will benefit students in future standardized exams as well as in their professional practice.

Background

Over the past 20 years, many medical schools have reduced or entirely eliminated hands-on teaching laboratories in medical microbiology courses [1]. In fact, according to a recent survey, just over half of medical schools included laboratory-based teaching methods in their preclinical microbiology curriculum [2]. This reduction comes despite recommendations by the Infectious Diseases Society of America to include hands-on laboratory exercises that expose students to microbiology techniques used for infectious disease diagnosis as part of preclinical microbiology courses [3]. Laboratory findings are critical for diagnosis, treatment, management, and prevention of infectious disease [4]. Skills related to identification and treatment of infectious organisms are of particular importance considering ongoing challenges with emerging infectious diseases and the increasing prevalence of antimicrobial-resistant pathogens. In addition, laboratory exercises emphasize the importance of careful observation and biological variability [5].

The ability to transfer basic science knowledge to clinical situations is essential for diagnosis and interpreting examination findings, and this transfer of learning is enhanced when students are given the opportunity to practice transference in multiple contexts [6, 7], such as in a classroom followed by a lab setting. Therefore, hands-on lab experiences provide opportunities for medical students to apply knowledge in a way that will benefit them as they transition into clinical training and practice.

Concurrent with the decline in microbiology laboratory offerings has been an increasing awareness of the benefits of active and collaborative learning in medical education. Kanthan and Mills [8] noted that the incorporation of active learning strategies in an undergraduate medical education course promoted social interaction and was regarded favorably by most students. The multi-sensory and team-oriented nature of a hands-on lab session engages students via several learning modalities, including visual (e.g., interpreting metabolic assays), auditory (e.g., discussion among group members), reading/writing (e.g., interpreting case scenarios), and kinesthetic (e.g., performing a bacterial stain). Therefore, this multifaceted learning environment benefits learners due to its ability to engage students with varying learning style preferences [9]. Furthermore, lab sessions enhance both long-term retention and short-term retention, presumably due to their active, collaborative, and visual nature [10].

In addition to the active nature of laboratory sessions, wet labs also provide exposure to the principles of the scientific method, concepts deemed important by the Liaison Committee for Medical Education (LCME). The LCME emphasizes the importance of educational efforts that promote familiarity with the scientific method in accreditation standard 7, element 3 (7.3 Scientific method/Clinical/Translational research). This element states that: “The faculty of a medical school ensure that the medical curriculum includes instruction in the scientific method…” [11]. Hands-on or simulated exercises in which medical students collect or use data to test and verify a hypothesis—such as in a clinical case–based microbiology lab where students generate a differential diagnosis—contribute to students’ familiarity with the concept of the scientific method. Instructional sessions that include more process-focused, experimental approaches that encourage students to use reasoning skills benefit learners in developing scientific abilities [12].

Besides the direct influence of laboratory-based learning on undergraduate medical training, the benefits of such instruction can extend into a student’s professional career as well. In a survey of graduating internal medicine residents, perceived infectious disease knowledge and self-efficacy correlated with exposure to active learning opportunities, specifically lab-based sessions in preclinical microbiology education. Moreover, residents planning to pursue an infectious disease fellowship were more likely to have received preclinical training that involved laboratory-based sessions [13].

Given the many benefits of laboratory-based learning, it seems reasonable that labs should be a fundamental component of microbiology teaching. However, a number of factors, including curricular changes and limited availability of appropriate resources, have contributed to the elimination of laboratory sessions from microbiology curricula [1]. The resources required for conducting a hands-on laboratory course are inherently different from those needed for more traditional classroom-based or computer-assisted learning. Laboratory courses require adequate space to accommodate hands-on work as well as financial resources for lab materials. Faculty and support personnel must commit time to prepare instructional materials, lab supplies, and live cultures in addition to facilitating the lab sessions. Ensuring a safe learning environment is of paramount importance when working with infectious agents. Because of these constraints, computer-based lab modules have been developed and deployed in lieu of or in conjunction with traditional wet labs [14].

Until 2009, second-year medical students at Tulane University School of Medicine participated in mandatory wet lab sessions, which were held once per week throughout the 6-week Medical Microbiology course. Due to the significant restructuring and integration of the second-year curriculum, these mandatory wet labs were discontinued. However, in response to student requests to reestablish the wet lab, a one-time voluntary session was designed and implemented in 2011, to be conducted during the Basic Infectious Diseases (Basic ID) module.

In this study, we sought to analyze the impact of a voluntary hands-on microbiology laboratory session on students’ knowledge retention, particularly their ability to apply the underlying principles to exam questions in the Basic ID module. Because the laboratory sessions were voluntary, we were able to directly compare exam outcomes between students who participated in the lab session with those who did not. With other factors being the same within each year of our study, such as instructors and material presented in classroom-based sessions, as well as exam format and content, this retrospective analysis provided a unique opportunity to establish the effects of a laboratory session on knowledge retention.

Methods

Laboratory Session

A 2-hour voluntary lab session is offered during the Basic ID module in phase II to supplement the material presented in the classroom setting and provide an opportunity for students to perform routine microbiological assays. Students are aware that neither their attendance nor performance in the laboratory session has any direct impact on their course grade for the Basic ID course. The learning objectives for the lab session are as follows:

Identify etiologic bacterial organisms in clinical case studies based on the following:

• Discriminating between pathogenic and commensal organisms

• Performing and microscopically examining a Gram stain

• Interpreting metabolic and biochemical tests

• Assessing antibiotic sensitivity

The phase II curriculum begins toward the end of the first year (M1) and continues throughout all of the second year (M2) of medical school. Our phase II curriculum consists of five different courses: Immunology, Introduction to Infectious Diseases (IID), Pharmacology, Mechanisms of Disease, and Clinical Diagnosis (see Fig. 1). Other than Immunology, these courses run throughout the organ-system-based modules across the second year. The Basic ID module is the second module in phase II of our integrated curriculum and is focused mostly on medical microbiology, immunology, as well as pharmacology topics. The remainder of the IID sessions are integrated within the systems modules. No further wet lab sessions are held during the systems modules.

Fig. 1.

Phase II curriculum. The phase II curriculum begins toward the end of the first year (M1) and continues throughout all of the second year (M2) of medical school. Most modules are approximately 3 weeks long. The voluntary wet lab session is offered during the third week of the Basic ID module (as indicated by the red arrow), when students are already familiar with basic bacteriology and the relevant routine microbiological assays through didactic lectures

All students in the course had access to optional online lab modules (http://learn.chm.msu.edu/vibl/index.html), which include detailed descriptions and animations of various laboratory techniques. However, the voluntary session was the only hands-on lab–based medical microbiology learning opportunity within our IID course. The lab is scheduled at a time that does not conflict with other required activities or classes for the phase II students.

In addition to the online materials, students receive prepared background information prior to the lab session, which includes necessary flowcharts for bacterial identification based on Gram reaction and explanations of how to perform and interpret essential microbiological assays. As an example, Fig. 2 presents a flowchart provided to students for identification of Gram-positive bacteria. These documents are available online and students bring copies of the protocols and identification guides to the lab session. During the laboratory session, students work in groups of 2–3 to determine the etiologic agents in two case-based scenarios, an example of which is shown in Box 1.

Fig. 2.

Representative pre-lab material distributed to lab attendees. This flowchart for identification of Gram-positive bacteria guides students in identifying Gram-positive organisms based on their interpretation of their appearance on blood agar plate (BAP) and other media as well as enzymatic assays and antibiotic susceptibility. Students receive a similar guide for Gram-negative organisms

Example Case Scenario Presented to Lab Attendees

Students receive two case scenarios as part of the introductory material provided at the beginning of the lab session. They are then able to initiate their differential diagnosis and proceed with determining which assays are required for confirmation based on flowcharts provided prior to the lab session (see Fig. 2).

Each group works toward their own differential diagnosis although faculty members are present during the lab session to provide guidance to the students as needed.

Because of the nature of bacterial cultures, assays requiring overnight incubation are inoculated prior to the lab for attendees to interpret. These include blood agar plates with isolated colonies of the organisms of interest, antibiotic sensitivity plates, and some metabolic assays, such as triple sugar iron and MacConkey agar, bacterial motility, etc. Attendees perform assays that provide more rapid outcomes during the lab session, such as a Gram stain and oxidase and catalase tests, as indicated by the flowcharts provided.

Participants

Exam data were collected from students enrolled in the IID course from 2011 to 2017. Total course enrollment varied from 183 to 199 students each year, with a total of 1327 students enrolled in the IID course over the 7-year period. Students participating in the wet labs initially signed up online and also signed an attendance sheet during the wet lab session. This study was approved by the Tulane University Institutional Review Board.

Measures

Exam Performance

All exam questions were multiple-choice format. Data for seven academic years were analyzed in aggregate. Exam questions were prepared by individual instructors based specifically on the content of each session without regard to lab content. Students were separated into two groups for analysis based on their attendance at the voluntary lab session. Individual student performance in three categories was determined. These included (A) percent correct on questions directly related to wet lab content, (B) percent correct on all other questions not related to lab content, and (C) percent correct on the overall exam. Prism software (GraphPad, version 7.0, La Jolla, CA) was used for all statistical analysis. Exam performance datasets were compared using a Mann-Whitney test. All results were deemed significant at p < 0.05.

Student Evaluations

We analyzed responses from routinely collected module evaluations in which students indicated whether the lab session was “beneficial and contributed to overall learning” using a Likert-type scale of 1 (strongly disagree) to 5 (strongly agree). The number of responders indicating the voluntary lab was beneficial with a response of either “Agree” or “Strongly Agree” was recorded relative to the total number of responders for that specific question. We also collected the mean of the reported responses each year. Evaluation data were available for all but 1 year of the period 2011–2017.

As part of the module evaluations, students also provided comments regarding the wet lab session and its contribution to their overall learning. Comments that directly pertained to the lab session for all years of the period 2011–2017 were collected and entered into an online word cloud generator (Wordclouds.com). The program determines the frequency of use of each word found in the comments, generating a word cloud with the font size proportional to the number of times that word appears in the text.

Results

Lab Attendance

Enrollment in the voluntary wet lab session varied each year from 16 to 43 students. The student to faculty ratio was approximately 8:1 each year. Overall, 204 students attended the voluntary lab session from a total of 1327 second-year students over the 7-year time period. This represented 15.3% of medical students over the course of the study, with a yearly attendance minimum of 8.7% and a maximum of 22.0%, as shown in Fig. 3. We did not observe an obvious trend in attendance numbers (consistent increase or decrease) during the 7 years the lab was offered, although there was a spike in attendance in 2017–2018. This spike was likely due to a poster presentation of our preliminary findings within a School of Medicine education conference. This suggests that while the evidence of its benefit did encourage more students to participate in that particular year, overall the majority of students either did not expect the lab to contribute to their understanding, felt it was not a valuable investment of their time, or had other time commitments that precluded their attendance at the voluntary session.

Fig. 3.

Lab attendance over the 7-year study period. The percentage of students attending the voluntary lab session was recorded relative to the total number of students in the Basic ID module for each academic year. The minimum attendance was 8.7% (2016–2017) and the maximum was 22% (2017–2018) with a yearly average of 15.3%

Exam Performance

We compared exam performance by attendees and non-attendees on the Basic ID module exam. Our analysis involved performance comparisons on two specific subsets of exam questions, which were (A) questions directly related to wet lab content and (B) all other exam questions, as well as (C) the overall exam. Students attending the wet lab session (mean rank = 728.9) performed significantly better on questions related to lab content than non-attendees (mean rank = 652.3, p = 0.0074), as shown in Fig. 4. Therefore, student comprehension and retention were significantly improved by attending the voluntary lab session. When comparing performance on exam questions unrelated to wet lab content, there was no difference in performance between attendees (mean rank = 692.0) and non-attendees (mean rank = 658.9) (p = 0.2577). On the overall exam, attendees’ performance (mean rank = 704.9) was comparable to non-attendees (mean rank = 656.6) (p = 0.0985). The lack of significant difference between attendees and non-attendees on the non-related questions suggests that the increase in performance was attributable to lab attendance and not a result of lab attendees representing an overall higher performing subset of students or those with a stronger background in microbiology. Anecdotally, we noted that students who attended the lab had varied backgrounds with regard to lab techniques. While some had previous experience in bacteriology, many who participated in the lab session had never had such an opportunity to work with live cultures or use a microscope.

Fig. 4.

Student exam performance. A comparison of lab attendees’ and non-attendees’ performance on a questions related to lab content, b questions not related to lab content, and c all exam questions was performed. Boxes represent the 25th to 75th percentiles with lines indicating median values. Bars (whiskers) represent minimum to maximum data values. Mean rank values for each dataset appear below the respective bar plots. Data were analyzed using the Mann-Whitney test with p values associated with significant differences between groups indicated (n.s., non-significant)

Student Evaluations

Of the evaluations received, the majority of responders (yearly average = 63.75%, min 48.8%, max 88.1%) indicated the voluntary lab was beneficial toward their overall learning with a response of either 4 (Agree) or 5 (Strongly Agree) on a Likert-type scale of 1–5, as detailed in Table 1, with an average score of 3.96 (min 3.63, max 4.34). Because evaluation responses were anonymous, we were unable to distinguish responses from those who actually attended the lab. In fact, the number of responders to the quantitative survey questions exceeded the number of attendees by at least 45% each year (as presented in Table 1), indicating that students who made use of the online lab modules in lieu of attendance at the voluntary lab session likely responded to this question as well.

Table 1.

Student evaluation of the benefits of the lab session. As part of routine course evaluations, students were asked whether the lab session was “beneficial and contributed to overall learning” using a Likert-type scale of 1 (strongly disagree) to 5 (strongly agree). The percent of responders indicating “Agree” or “Strongly Agree” was recorded in addition to the average response each year, relative to the total number of responders for that specific question. The mean Likert scale score for each year was also noted

Year	% agree or strongly agree	Mean Likert scale score	Number of responders	Number of lab attendees
2011–2012	60	3.63	35	24
2013–2014	61.2	3.96	49	31
2014–2015	68.1	4.06	47	30
2015–2016	56.4	3.78	55	29
2016–2017	48.8	3.78	41	16
2017–2018	88.1	4.34	67	43
Average	63.7	3.96	49	28.8

Additionally, students’ comments that specifically pertained to the wet lab were entered into a word cloud generator. Figure 5 is a visual representation of the words and phrases provided by students with the font size of each word being proportional to its frequency in the student comments. The most notable feedback, as indicated by the word cloud, was that students found the wet lab “helpful” with the words “learning”, “understanding”, “enjoyed”, “great”, and “liked” mentioned with high frequency as well. Select student comments are provided below.

“It was really fun, and helped me to understand better the different tests used to differentiate bacteria. I found I remembered the specifics of each bacteria much better following the session.”

“This wet lab was highly helpful for understanding the lab assays that specific bacteria test positive and negative for. It figuratively ‘put a name to the face’ of various lab assays and allowed us to understand what we’re ordering when we’ll be ordering it in clinic.”

“Seeing how the plates and colonies actually looked under certain growth conditions was essential in helping the material stick.”

“Amazing! It made very esoteric things that seem imaginary when reading a text book or hearing about in a lecture very real and much more relatable.”

Fig. 5.

Student comments regarding the wet lab session. Student responses regarding the wet lab session and its contribution to their overall learning collected during routine course evaluations were entered into a word cloud generator. Word size is directly related to the frequency with which it appeared in student comments

These responses emphasize that students valued the opportunity to visually reinforce concepts they had previously read in a textbook or heard in lectures. They could also foresee the material they learned in the teaching lab being relevant to their future clinical practice.

Discussion

The voluntary nature of our microbiology lab session provided a unique opportunity to assess its impact on knowledge retention independent of other factors, such as classroom instructors, lecture, and exam content. The laboratory session, which followed the bacteriology component of the Basic ID module (see Fig. 1), provided an opportunity for students to revisit concepts initially presented in the traditional classroom setting. The lab session induces the practice of information retrieval, the benefits of which have been recently discussed by Gooding and coworkers for students in health-related curricula [15]. The opportunity to revisit learned material in a manner that is beyond merely recalling or reviewing the material in the same context as it was initially presented fosters better retention [16]. The timing of our wet lab session within the Basic ID module varied slightly each year from 3 to 10 days following the end of the bacteriology component of the Basic ID module. This time-based learning distribution, or spaced practice, has been shown to improve educational outcomes more so than back-to-back learning episodes [17].

In addition to the benefit of reexamining material from previous learning sessions, the specific nature of the laboratory work also allows students to apply and transfer previously presented concepts using patient-based scenarios. The prospect of subsequently organizing information within a clinically relevant framework in assessing the case scenarios benefits lab attendees [3]. The skills of application and transference contribute to improved retention and are important in professional careers in healthcare [15]. In addition, the active, collaborative, and visual components enrich lab-based learning opportunities [10].

Furthermore, lab sessions provide the opportunity for students to implement the scientific method in case-based scenarios, a skill that is important for the practice of evidence-based medicine and the ability to critically review scientific literature. Lab attendees’ approach to work up the patient cases exemplifies the LCME’s definition of “Scientific Method” relating to Element 7.3. The LCME provides the following definition: “Scientific method: A method of procedure consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses. Typically, the method consists of the following steps: 1) identifying and defining a problem; 2) accumulating relevant data; 3) formulating a tentative hypothesis; 4) conducting experiments to test the hypothesis; 5) interpreting the results objectively; and 6) repeating the steps until an acceptable solution is found” [11]. Students have the opportunity to develop a differential diagnosis, test their hypothesis using the lab tests available, compare their results with the framework (flowchart) provided, and ultimately come to a conclusion of the causative agent.

Our analysis of student evaluations indicated that in general, students expressed an appreciation for the lab’s contribution to their overall learning of the material in the IID course. This is likely, in part, due to the problem-solving nature of the lab session. A recent report of student perceptions in an undergraduate physics lab suggests that students favor less prescribed/structured labs that have more open-ended outcomes [12]. Students and faculty facilitators as well benefit from the interactions and discussions that arise during the course of the lab session, and students tend to feel more comfortable approaching these faculty members even beyond the Basic ID course.

Because of the anonymity of the evaluation responses, we were unable to distinguish between students who participated in the hands-on lab session from those who viewed the online lab module or those who took part in neither. While it would be interesting and informative to be able to differentiate student perceptions and comments regarding the usefulness and benefit of a hands-on lab session as compared to the online tutorials, the anonymous nature of our data from course evaluations did not allow for this comparison. This is a concept that merits investigation in future studies.

Conclusions

At a time when many medical schools are reducing or eliminating hands-on lab sessions in microbiology and other basic sciences as well, our results highlight the benefits of this teaching strategy. The nature of our wet lab session provides a mechanism for incorporating hands-on microbiology into the undergraduate medical curriculum, if even on a voluntary basis. The collaborative, active learning that occurs contributes to students’ perceived value of the lab session as well as their superior performance on exam questions related to presented material. While our results are based on course examinations completed within 1 week of the lab session, we expect that the improved understanding of concepts reinforced during the lab session also contributes to enhanced long-term retention that extends to future standardized exams as well as professional practice.

Abbreviations

Basic ID

Basic Infectious Diseases

IID

Introduction to Infectious Diseases

LCME

Liaison Committee for Medical Education

Authors’ Contributions

LBL contributed to the design of the study, assisted with data interpretation and statistical analysis, and wrote the manuscript. CML performed data collection, analysis, and interpretation and contributed to manuscript preparation. JWG assisted with data collection and interpretation, statistical analysis, figure design, and manuscript preparation. KHzB contributed to study design, data interpretation, figure design, and manuscript preparation. All authors read and approved the final manuscript.

Compliance with Ethical Standards

Ethics Approval and Consent to Participate

This study was approved by the Tulane University Institutional Review Board.

Competing Interests

The authors declare that they have no competing interests.