C 2006) Annals of Biomedical Engineering ( DOI: 10.1007/s10439-005-9030-3
Educational Methods and Best Practices in BME Laboratories1 ERIC J. PERREAULT,1 MITCHELL LITT,2 and ANN SATERBAK1 1 Department of Biomedical Engineering, Northwestern University, Chicago, IL; 2 Department of Bioengineering, University of Pennsylvania, Philadelphia, PA; and 3 Department of Biomedical Engineering and Physical Medicine and Rehabilation, Northwestern University 345 E. Superiot St./Smpp1403, Chicago, IL 60611
(Received 28 March 2005; accepted 27 July 2005)
INTRODUCTION Biomedical engineering (BME) is a practical discipline and laboratory courses that teach the practice of this discipline are an integral component of an effective undergraduate curriculum. Laboratory courses provide students with the opportunity to observe how the physical world compares to the quantitative descriptions of that world taught in the classroom. They also should provide students with the skills necessary for enhancing our descriptions of the physical world, for developing the tools required to interact with that world on a variety of scales, for designing experiments to accomplish these goals and for effectively communicating the results of these experiments. The purpose of this document is to outline the critical components of an effective BME laboratory curriculum and teaching methodologies most appropriate for delivering the content of that curriculum. The content is based upon a white paper submitted in advance of the second Biomedical Engineering Education Summit (BEES II) sponsored by the Whitaker Foundation, and on the discussions that occurred at that summit. BME is a broad discipline that integrates knowledge from the physical, chemical, and engineering sciences for application to the study of biology and medicine. The challenge in developing an undergraduate BME curriculum is determining how to provide students with the breadth required to understand the interdependence of these disciplines as well as the depth necessary to apply the acquired knowledge throughout their careers. Laboratory courses can provide hands-on exposure to the practice of BME. However, because of limited time and resources, it is not possible to cover the tools and techniques spanning the entire field in any undergraduate curriculum. Hence, it is imperative that laboratory courses deliver a foundation to support the skills Address correspondence to Eric J. Perreault, Department of Biomedical Engineering and Physical Medicine and Rehabilation, Northwestern University, 345 E. Superior St./Smpp1403, Chicago, IL 60611. Electronic mail:
[email protected] 1 Prepared for the Whitaker Engineering Educational Summit 2005
that will be obtained as students pursue their independent careers. One approach to designing a BME laboratory curriculum is to determine the core competencies that are to be acquired by each student. Focus on core competencies rather than specific content, allows for developing guidelines that provide BME graduates with a common set of skills yet which also can be adapted to match the specific strengths and resources available at each institution. Discussion at the BEES II strongly supported the use of core competencies in the development of laboratory curriculum. It also was the consensus opinion that the specific content used in the teaching of these competencies should be matched to the undergraduate curriculum implemented at each university, but need not be common across universities. Hence, the curriculum portion of this paper focuses on the core competencies that most summit attendees felt could benefit from laboratory instruction. In addition to the discussion at the BEES II, the core competencies outlined below were constructed with reference to three efforts to determine core competencies in engineering, the CDIO Syllabus3 (www.cdio. org), the VaNTH Core Competency Taxonomy7 (www.vanth.org/curriculum), and an effort at Rice University to coordinate laboratory courses across engineering and science curricula9 (http://www.owlnet. rice.edu/∼labgroup/labcourses.html).
CORE COMPETENCIES FOR UNDERGRADUATE LABORATORY INSTRUCTION Engineering Reasoning and Problem Solving Engineers need to be able to solve problems in an efficient manner. The initial step in this process is problem identification, for a solution it is effective only if it targets the appropriate problem. Once the problem has been recognized, a plan of attack needs to be devised. Students should be capable of formulating logical approaches to problem
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solving and of assessing the potential outcomes of their approach prior to implementation. The use of quantitative models can be an integral part of experimentation, inquiry, and estimation. BME undergraduates should be able to construct and use such models for estimating expected outcomes and the effects of experimental uncertainty. Acquisition and transfer of knowledge is essential for effective problem solving in novel areas. Hence, BME undergraduates should be facile at applying the quantitative techniques taught in the classroom to novel problems and at accessing information about new techniques that may be relevant to those problems.
Experimental Design and Data Analysis Hypothesis driven experiments form the basis of the scientific method. To be proficient in this methodology, undergraduate engineers should be capable of formulating testable hypotheses that address the critical aspects of a given problem. Such hypotheses should be constructed in the context of previous results and should be tested along with control studies that explore viable alternatives. Instruction in the design of experiments will allow students to develop efficient tests that generate an appropriately rich set of data. An efficient experimental design also will help in the design of effective analyses. Students should be familiar with determining if the planned analyses are sufficient for testing the proposed hypothesis.
Making Measurements and Interpreting Data from Biological Systems Biomedical engineering is distinguished from other engineering disciplines by the need to make reliable, quantitative measurements from biological systems without damaging those systems. Hence, BME undergraduates should be aware of the issues relevant to interfacing technology with biological systems and using that technology to obtain reliable measurements. Biological measurements span the range from sub-cellular to organismal, and BME undergraduates should be aware of the challenges and techniques relevant to making measurements across these size scales. They also should be able to use these measurements to obtain quantitative, systems-level characterizations of biological systems and to interpret their results in the context of prior knowledge.
Laboratory Technique Proficiency in laboratory techniques is necessary for conducting successful experiments. As such, students
should be trained in appropriate record keeping principles and careful experimentation. They also should be aware of the importance of laboratory safety and the appropriate protocols that need to be followed in the event of an accident. For BMEs, this training should include the appropriate handling and disposal of biological tissues, in addition to the safety procedures common to other fields of engineering and science. Finally, students should be able to recognize when an experiment is not working properly and be able to troubleshoot the cause of any unexpected behavior. Accomplishing this goal requires designing laboratory challenges that give students sufficient opportunities for exploration and failure as well as the opportunity and guidance to overcome these failures.
Communications Because the result of an experiment is to generate knowledge, an experiment only can be successful if its results are communicated effectively. Hence, laboratory courses are a logical venue for enhancing communication skills, especially those related to the delivery of technical and scientific information. Students should be able to present laboratory findings in a logical and concise manner, and should be knowledgeable regarding how experimental data can be used to support arguments in a persuasive manner. They should be proficient in presenting these results in written or oral form and in targeting their presentation to audiences with a range of backgrounds. The latter is especially important when presenting the technical aspects of their work.
Maturity and Responsibility To be effective in the workplace, engineers need to be mature and responsible. The laboratory setting provides an opportunity to demonstrate and develop these skills, and students should be given this opportunity. This can be accomplished by requiring effective advance preparation before prior to entering the laboratory, giving students the opportunity to work independently and teaching them how to be effective when working as a part of a team. METHODS OF LABORATORY INSTRUCTION Specifying the curriculum for undergraduate BME laboratories is an important and necessary first step in laboratory program design. However, the effectiveness of any curriculum is linked not only to the content of that curriculum but also to the teaching methodologies used to deliver that content. Hence, an effective curriculum should be developed
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in parallel with the instructional methods that will optimize the learning of each competency or topic. Typical instructional methods used for laboratory courses include the following: Lectures: An instructor presents a lecture, in classroom or lab, usually prior to the lab session, covering the theory behind the key concepts, the experimental methods to be used, and the analytical techniques needed for calculating results and for comparing them to control and literature values. Pre-Laboratory Exercises: In many instances, it may be desirable to have students become familiar with conceptually challenging or critical topics prior to entering the laboratory. This can be accomplished through the use of pre-laboratory exercises. The exercises may range from reading literature and doing computational examples to designing experimental protocols and equipment setup, preparing solutions to mathematical models of the experimental system, and running a virtual experiment of the actual equipment provided on line. Demonstration Exercises: These are the focus of many laboratory courses, especially at the introductory level. These typically involve providing students with a set of instructions and protocols that will allow them to complete one or more pre-designed experiments. Evaluation is based on the degree of agreement with expected or literature results. It is intended to demonstrate that the accepted values in the literature are correct, testing the students’ ability to reproduce earlier results by others. Inquiry-Based Learning (IBL): The purpose of IBL or active learning is to enhance students’ understanding of key concepts by forcing them to apply their knowledge of these concepts in a novel manner. The use of IBL approaches has been demonstrated to promote deeper learning and improve attitudes towards learning and knowledge acquisition.8 A typical approach is to provide students with a specific challenge related to the conceptual topic of interest and to require them to address that challenge as they see fit. In this paradigm, students are responsible for all aspects of the experimental design, protocol, and operation, as well as analysis (including statistics) and reporting. IBL differs from original research in that the results are usually already known in the literature, and that the challenge to the students is to show how and why their results agree with or differ from accepted values and in what way their experimental design explains agreement or differences. Each of these models has advantages and disadvantages, depending on the objectives and content of each experimental topic. However, it is our belief that IBL is the most effective way to teach critical concepts and that this approach should be used when applicable in
laboratories courses ranging from the freshman to the senior year. The remainder of this section outlines the advantages of IBL and provides examples of how it can be integrated into different aspects of laboratory instruction.
The Use of Inquiry-Based Learning in the Laboratory Research into the development of expertise has shown that this development is linked to the acquisition of deep, well-organized bodies of “conditionalized” knowledge.5 Conditionalized knowledge is that developed along with an understanding of the context in which it may be applied.1 The laboratory is an ideal setting in which to develop conditionalized expertise as it provides students with the opportunity to apply their knowledge. The goal of educators is to maximize the benefit that can be obtained from laboratory exercises. The Legacy cycle2,10 provides one framework for incorporating IBL into the laboratory. It is an approach consistent with the principles outlined in How People Learn, a report by the National Academy of Sciences on recent developments in the science of learning.1 The Legacy cycle details the process of using guided challenges to foster the acquisition of conditionalized knowledge, and is an effective means to enhance laboratory instruction.4,6 Each cycle begins with a challenge that is consistent with the objectives of the course. The purpose of each challenge is to provide students with a complex goal that encourages inquiry and requires the application of key concepts in a context appropriate manner. Other elements of the Legacy cycle include providing students with the opportunity to generate initial ideas, to compare these ideas with those proposed by multiple experts in the field, to research and revise their approach to the challenge through a series of guided learning activities and to be assessed in a formative manner. The final stage of each cycle incorporates some form of summative assessment, such as a presentation, report, quiz, or final exam. While each objective in a laboratory course may not require all components of the Legacy cycle, the concepts of challenge, research, and formative as well as summative assessment are fundamental to the use of IBL. It should be noted that while we believe that inquiry should be at the core of effective laboratory instruction, inquiry on its own is not sufficient. Rather, it often needs to be paired with the more traditional instructional methods listed above to meet the course objectives. Lectures often are necessary during the introduction or review of key concepts relevant to the core challenge, pre-laboratory exercises can be used to enforce key concepts or to guide the learning process during the course of inquiry, and
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demonstration exercises can be used to introduce laboratory skills that may be necessary for meeting the primary challenge. The challenge itself will reinforce the concepts introduced through these additional instructional methods by providing a unique context for the application of the desired knowledge. Inquiry-Based Learning for the Development of Core Competencies Laboratory exercises developed to encourage student inquiry are an effective way to incorporate the four of the six proposed core competencies into the BME laboratory curriculum. Presenting students with a challenge or series of guided challenges in laboratory courses requires them to use and further develop their engineering reasoning and problem solving skills. It also provides them with an opportunity to practice the art and science of good experimental design and teaches the importance of linking this design to effective data analysis techniques prior to the start of experimentation. The application of engineering and statistical analysis techniques to the data collected from a student-designed experiment provides a unique opportunity for knowledge transfer and conditionalized learning. In contrast to IBL approaches, more traditional methods of laboratory instruction, such as demonstration exercises, are not as effective for teaching the core competencies of problem solving and experimental design because they do not provide an equivalent opportunity to develop conditionalized learning. Most methods for laboratory instruction offer the opportunity to develop communication competencies. The use of effective oral, written, and technical communications can be incorporated into most teaching methodologies for BME laboratories. The advantage of IBL is that it provides students with a sense of ownership in their work. The freedom to be creative that is fostered by inquiry-based approaches to laboratory exercises can enhance the motivation to communicate the results of IBL exercises in an effective manner. With the freedom to create comes the responsibility to focus efforts, to recover from mistakes, and to work effectively as a team. Hence, the competencies of maturity and responsibility also are inherently part of a curriculum based on IBL. The ability to make specific biological measurements and the development of effective laboratory technique are the two core competencies that should be developed prior to or in parallel with IBL approaches for laboratory instruction. Proficiency in setting up and using simple and complex apparatus, as well as such learning such principles as record keeping, safety, and accident protocols, using and properly disposing of biological materials, and troubleshooting, is not learned efficiently during inquiry or even demonstration, especially when these techniques
are used on a group level. Efficient group work requires division of labor, so that the techniques learned depend on what each student does. Learning techniques first requires demonstration followed by individual practice. This practice could be accomplished in the form of individual prelaboratory exercises or in a course focusing on technique (e.g. tissue culture). However, the use of pre-laboratory exercises prior to laboratory modules based on IBL allows for the immediate transfer of laboratory technique to application and the associated development of conditionalized knowledge.
IMPLEMENTATION EXAMPLES There are multiple approaches for developing laboratory classes that focus on the development of core competencies. This section provides two such examples that illustrate how many of the concepts discussed above may be incorporated into the BME laboratory. The first example is drawn from a senior-level laboratory course at Northwestern University and the second from a series of two laboratory courses taught at Rice University. These examples have been chosen to emphasize how core competencies can be developed across different technical areas ranging from bioinstrumentation and experimental design to tissue engineering. Northwestern University—BME 308 BME 308 is a 10-week, senior-level laboratory course taught at Northwestern University. The course is designed to develop competencies in each of the six areas outlined above. These competencies are developed primarily through a set if IBL modules. Five 2-week modules are incorporated into the course. Each module consists of two, 4-h lab sessions supplemented by up to six 2-h lectures. The lectures are used to introduce engineering concepts (e.g. instrumentation fundamentals, digital signal processing, statistical design of experiments . . .) and to provide examples of how these concepts can be applied to the study of biological systems. The laboratory exercises provide an opportunity for the students to apply these concepts. The initial modules in the course begin with laboratory demonstration exercises that are used to familiarize students with novel equipment and measurement techniques. Typically, these exercises are performed in the first lab session. During the second session, students are presented with a set of goals or questions related to the concepts being taught rather than a set of instructions. These latter IBL components are designed to foster conditionalized expertise and problem solving skills. As the course progresses, there is a transition from labs that have roughly equal components
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of demonstration exercises and IBL components to those that incorporate only IBL. However, even in these final IBL modules, the 2-week cycle of the lab is used to transition students from guided learning to independent learning. One specific example is provided below.
A Laboratory Module for Teaching Hypothesis-Driven Experimental Design The final module in BME 308 is designed to teach the principles of hypothesis-driven experimental design. Two types of experiments are used to teach these concepts; each requires the measurement of biopotentials, which is covered in an earlier lab session. The first class of experiments examine the relationships between surface electromyograms (EMGs) from the biceps muscle and elbow torque, and the second examines voluntary reaction times in response to visual stimuli; student groups are randomly assigned to one of the two experiments. During the first lab session, students are presented with a specific hypothesis and are required to design an experiment and the associated analyses to test this hypothesis. No further instructions are provided other than the manuals for sensors that have not previously been used. This initial hypothesis is trivial, and has been selected for the purpose of familiarizing the students with the measurements that are to be made and the associated analyses that can be used to process these measurements. For example, the initial hypothesis for the EMG-force experiments is that, during isometric contractions, EMG amplitude increases with increasing joint moment. Testing this hypothesis requires students to determine how to quantify EMG amplitude and elbow moment during isometric contractions, thereby providing familiarity with the experimental apparatus. They also are required to select the most appropriate statistical techniques for analyzing the resulting data, among those covered during the previous lectures. Based on this experience, students are required to propose their own hypothesis that will be tested in the second lab session. A few skeleton hypotheses are presented as examples and approximately half of the students build upon these examples. The remaining half develops novel hypotheses related to one of the two classes of experiments. Prior to returning for the second lab session, students are required to present a detailed experimental design and to have this design approved by the instructor. Students are given an ungraded critique of this design prior to entering the lab, thereby providing an important formative assessment of their current progress. The second session then is used to complete the proposed experiments. The final sum-
mative assessment for this lab module is based upon a written report submitted by the entire group. Reports are graded according to the significance of the proposed hypothesis, the quality of the experimental design and the collected data, the appropriateness of the selected analyses, the interpretation of the results, and the quality of the written material. All students in a group receive the same grade for the report. Additional, individual assessments are used through the course to differentiate between the members of each group. Rice University—BIOE 342 and 442 Two laboratory courses focused on tissue engineering, BIOE 342 and BIOE 442 (http://www.ruf.rice.edu/ ∼bioewhit/labs.html), are taught to undergraduates in the Bioengineering Department at Rice University. The content of these courses supports the department’s emphasis on biomedical engineering at the molecular, cellular, and tissue levels. Within this sequence of courses, all six of the aforementioned core competencies are addressed. BIOE 342 is a required five-week junior-level course with approximately 12 h of individual laboratory time and one h of lecture per week. The purpose of this course is to provide students with the laboratory techniques and quantitative analysis tools necessary to operate independently in a cell and tissue engineering laboratory. Because techniques such as sterility are essential for preventing gross contamination, teaching in BIOE 342 is done primarily in demonstration mode. Core competencies that are stressed include the development of laboratory technique, making measurements from biological systems, quantitative data analysis and interpretation, communication skills, and independent working. Specific content that is taught includes maintaining cells in culture, assessing cell morphology and confluency visually, and quantitatively assessing cell viability, attachment, and proliferation. In contrast, BIOE 442 is an IBL course that focuses on the application of tissue culture techniques to a tissue engineering challenge. This laboratory emphasizes all six core competencies, particularly problem solving, experimental design, and trouble-shooting. It is a senior-level elective, taken by more than half of the students, that lasts for six weeks and contains approximately 12 h of laboratory per week; no lectures are presented. In this course, students work in groups of two. BIOE 442 builds upon the skills developed in BIOE 342. In addition, students are taught how to synthesize poly(L-lactic acid) (PLLA) and characterize the physical and chemical properties of PLLA and poly(DLlactic-co-glycolic acid) (PLGA). These additional skills are applied in the completion of a four-week degradation study of PLLA and PLGA films at physiological temperature and pH.
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The challenge in BIOE 442 is to quantify the viability, attachment, and proliferation of fibroblast cells on PLLA films. This open-ended challenge is presented in the second week of the course. Students are not given protocols for these experiments. Rather, they must be developed or adapted from BIOE 342 and adjusted for differences such as cell seeding levels, attachment kinetics, and proliferation rates. Students also are required to design their own experiments, including the number of repeat tests, type and number of controls, cell seeding concentrations, test and control surfaces, etc. While many of the experiments parallel those in BIOE 342, several differences are also critical. For example, cells attach to a lesser degree on the PLLA as compared to the tissue culture surface. Students have to do substantial planning. For example, students have to manage their flasks of cells so that the cells are confluent on the days that they are needed for particular experiments. Most students repeat experiments with a redesigned protocol. Because of the open-ended nature of the assignment, students develop unique approaches and protocols. With the experimental challenge posed, this IBL laboratory is consistent with the Legacy cycle. The assignments and grading for BIOE 342 and BIOE 442 involve formative and summative assessment; all grading is on an individual basis. In BIOE 342, the weekly, written assignments are geared to reinforce observational skills, analytical thinking, statistical comparison between treatments, and comparison between experiments. At the end of the lab, students prepare a technical poster, which covers the objectives, methods, experimental results, and implications of the work. Following extensive instructor feedback that serves as important formative assessment, the students revise their work and turn in a final technical poster. Students also are graded on their tissue culture skills and safety in the lab. In BIOE 442, each student writes a research paper summarizing the developed methods and results of their experiments. A draft of the paper is graded, which provides formative assessment; however, the majority of the grade is based on the revised research
paper, which provides summative assessment. The papers are evaluated on clarity of writing, design of experiments, presentation of data, and analysis and interpretation of data.
CONCLUSIONS AND RECOMMENDATIONS Laboratory courses are an essential component of the BME undergraduate curriculum. They provide the opportunity for the development of conditionalized knowledge that can provide students with the skills necessary for transferring classroom experiences to a range of novel situations. Laboratory courses also can be used to develop the core competencies that define a BME undergraduate. Such a design allows for a flexibility that can be matched to the strengths and overall curriculum of each institution while still providing a common skill set for all BME undergraduates. The core competencies outlined in this report are those that most BEES II attendees agreed could benefit from laboratory instruction. Our vision is that more BME laboratories will be designed to develop these competencies directly. While this is the practice at some institutions, discussions at the BEES II workshop indicated that it is not yet widespread. The use of IBL is an effective means for developing core competencies, and BEES II attendees were in strong agreement that laboratory instruction should be structured to incorporate IBL, whenever possible. Again, although the value of this practice was acknowledged widely, representatives from most institutions indicated a desire to incorporate additional IBL modules into their laboratories. The course descriptions given above provide examples of how these principles may be put into practice in courses with diverse aims. In the future, it would be advantageous to have a resource for sharing detailed laboratory instructional materials that adhere to the principles outlined in this document.
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ACKNOWLEDGMENTS The authors thank the Whitaker Foundation for organizing and supporting the BEES II. They also would like to thank Drs. Robert Linsenmeier and Jay Walsh for reviewing early versions of the manuscript. REFERENCES 1
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