Effectiveness of challenge-based instruction in biomechanics Journal of engineering education, 2006(4) 報告人：楊易霖
Abstract • Studies were designed to determine the effectiveness of challenge-based instruction (CBI) versus traditional lecture-based instruction. • Comparisons were made over a three-year period between student performance on knowledge-based questions in courses taught with taxonomy-based and challenge-based approaches to instruction. • When performance on all questions was compared, CBI classes scored significantly better than control classes on 26 percent of the questions, while control classes outperformed CBI classes on eight percent of the questions, but there was no significant difference in overall performance. • However, students in CBI classes performed significantly better than students in control classes on the more difficult questions (35 percent versus four percent).
Abstract • We attribute these differences to additional opportunities available in CBI classrooms for learners to examine their conceptual understanding. • Student surveys indicate a slight preference for the challenge-based approach. • We believe that the challenge-based approach is effective and has the potential to better prepare students for the workplace and for life-long learning. • Keywords: challenge-based instruction, How People Learn (HPL), STAR Legacy Cycle
摘要 • 本研究比較挑戰式教學(CBI)與傳統講授式學教的成效。 • 為期三年的比較研究，以知識為基礎的問題測量學生在傳統與CBI教學的表現。 • CBI班級在26%問題中的分數，優於控制組；控制組在8%問題中的分數，優於CBI，但整體表現沒有差異。 • 但是，CBI班級在較困難的問題中，表現於優控制組(35%vs4%)。 • 此歸因於CBI班級的學生獲得額外的機會，檢視他們概念性的理解。 • 學生對於CBI有少量的偏好。 • 作者相信此方法是有效的，且能潛在地使學生針對未來工作與終身學習有較好的準備。
Outline • Introduction • Active learning and the “How People Learn” framework • Problem-based learning • Challenge-based instruction • STAR legacy cycle • Objective of this study • Method • Control • Treatment • Comparison studies • Instructors • Course content • Instruments and measures
Outline • Result • Instructional practices • Test for CBI instructor bias • Test for semester bias • Student performance • Student evaluations of CBI course • Discussion • Conclusions
Introduction • Active Learning and the “How People Learn” framework • Active learning can be defined as any instructional method that engages students in their own learning process by encouraging them to think about what they are learning and how well they are learning it. • However, engineering instructors often introduce new material without relating it to concepts that are more familiar to the students. • Thus, an effective way to learn the material is through the process of inductive learning in which the topic is introduced in terms of specifics, and advances to more general abstract concepts only when the students' need to know has been established. • The key finding is that effective learning environments are those that center not only on the knowledge to be gained, but also on the learners, assessment methods, and issues of community.
Introduction • Active learning environments naturally center on the learner's acquisition of new knowledge and involves interactions between the learners to form a community. • Despite their effectiveness, not many engineering faculty have introduced active learning, or HPL techniques, into their classrooms. • In addition, the strong emphasis on analytical problem solving is not as important to industry as the need to foster innovative engineers with strong communication skills and open-ended problem solving skills.
Introduction • Problem-based learning • The need for a new paradigm in medical training was recognized some years ago, and a number of medical schools adopted a particular form of active learning, known as problem-based learning (PBL). • The PBL approach introduced by Barrows • (1) learning must be studentcentered • (2) learning must occur in small groups with the assistance of a tutor • (3) the tutor acts as a facilitator • (4) authentic problems are presented before any preparation or study has occurred • (5) the problem is used to introduce the concepts and problem solving skills necessary to solve the problem • (6) new information needs to be acquired via self-directed learning. • Successful implementation of PBL hinges largely on finding the proper balance between self-discovery and direct instruction provided by a qualified instructor.
Introduction • Challenge-based instruction • Challenge-based instruction (CBI) is an anchored inquiry instructional method that shares similar theories for learning as problem-based learning. • The CBI approach is further informed by principles of learning and instruction inspired by the HPL Framework, and has been adopted by the Vanderbilt-NorthwesternTexas-Harvard MIT ERC in Bioengineering Education Technologies (VaNTH). • Several principles of CBI provide the rationale for why the method is effective for learning. • challenges can provide a context for the knowledge, which can facilitate students' application of this knowledge in future situations. • actively encouraging students to continually test their knowledge by articulating what they know in various contexts, and refine it to make it appropriate for all contexts, is a critical cycle in helping them generalize their knowledge and learn to apply it in novel contexts. • students need opportunities to refine what they know and reapply this knowledge to a variety of contexts.
Introduction • STAR legacy cycle • CBI employs an inductive learning method, with real life challenges providing the conditions and motivation for introducing new concepts and reinforcing old ones. • Most challenges follow an inquiry sequence using a modified form of the STAR Legacy Cycle, where STAR stands for Software Technology for Action and Reflection. • Use of the Legacy Cycle in CBI is useful because successful completion requires that students be exposed to all four dimensions of the HPL framework in each challenge. • CBI is based largely on PBL, but there are key differences. • where all discussion is done in a single small group. • requires that the facilitator be an expert in the subject matter, not simply a tutor. • where all lectures are eliminated.
Introduction • Objectives of this study • Since some studies report that engineering students generally prefer passive lectures to active learning methods, and since some PBL studies indicate negative effects when student knowledge was assessed, we were concerned that CBI might suffer similar difficulties. • Does this in-class trade-off between lectures and CBI activities result in diminished performance and deflated student attitudes toward learning? • Or, does this trade-off actually favor the CBI mode, particularly in regards to some of the more difficult concepts where more class time may be spent discussing these topics? • We hypothesize that students in a CBI class can devote more inclass time toward clarification of concepts, particularly the more difficult concepts. • We addressed this by comparing students' performance on final exam questions in different sections of the same course taught with two different instructional methods over a period of three years. • One section was taught by an instructor using a more traditional instructional method, while the other section was taught by another instructor using a challenge-based instructional design method.
Method • BME 101, an introductory course in biomechanics required of all biomedical engineering sophomores at Vanderbilt University, was selected for the comparison of traditional and CBI modes of instruction. • Control: "Traditional" Mode of Instruction • The traditional instructional model consists of lectures and instructor-centered problem-solving demonstrations during the class period, followed by student problem-solving activities after class. • The traditional instructional model provides a learning environment that centers largely on transmitting domain knowledge from the professor to the students via lecture, followed by assessment of students' learning at the end of each unit.
Method • Treatment: Challenge-based Model of Instruction • The CBI model uses a modular architecture to organize specific units of instruction around challenges that integrate important concepts in biomechanics. • An effective challenge-based course does not result from simply stringing together a number of unrelated challenge-based modules. • The transformed course was initially a mixture of traditional instruction, augmented with several challenge-based modules developed using the Legacy Cycle. • The number of modules increased with time and was supplemented by additional methods and tools. • A Classroom Communication System • Several short PowerPoint lectures with audio • Often students were asked to begin working homework problems in class • An online vector tutorial with pre-test and post-test sections • An online Free Body Diagram Assistant • Other diagnostic online assignments
Method • During the second year we also began to identify and test knowledge-based questions that could be used in the comparison study described below. • By the end of the second year, the entire course content was organized around challenges • On the first day of class, students in CBI courses were taught the fundamental principles of HPL, were introduced to the STAR Legacy cycle and classroom communication system, and were provided with the rationale for using challenge-based instruction. • Finally, students in both sections of the course were assured that although the instructional modes between classes would be different, the overall course content would be virtually identical.
Method • Comparison studies • A baseline study was conduced during the two years preceding initiation of the current study. • In this baseline condition we documented the existing instructional practice (i.e., traditional mode) using the HPL framework as a means to identify opportunities for enhancing the courses. • For three years after the baseline study we compared the CBI course taught in the Spring semester with the same course taught using the traditional model by a different instructor in the Fall semester. • To address whether a systematic difference existed between student preparation for Fall versus Spring classes, we gave a pre-test during the first week of class in the first year of the study. • Each year we compared students' performance on specific knowledge-based questions on the final exam, and on their perceptions of the course using a variety of surveys and questionnaires.
Method • Instructors • The senior instructor, and first author, taught the CBI sections and a more junior faculty member with research interests in biomechanics taught the traditional sections. • Course content • The control instructor was provided with all of the materials (lecture notes, homework questions, exam questions) used over the years in the course by the treatment instructor, and closely followed the "traditional" syllabus that was already in place. • In later years, the control instructor began to use some of the materials developed by the treatment instructor in the challenge-based course, including in-class formative assessment and technology tools, such as the Free Body Diagram Assistant for out of class assistance. • However, these HPL activities and techniques did not involve challenge-based modules. • The major distinction between the two methods of instruction, then, was that one instructor used challenge-based instruction and one instructor did not. • Observations made in both classes, discussed below, were made to help quantify in-class differences in HPL activities.
Method • Instruments and measures • Classroom Observations • We used classroom observations to assess the fraction of class time in CBI and traditional classrooms spent in HPL activities. • External observers from Vanderbilt's Peabody College used the VaNTH Observational System (VOS) to record the degree of interaction during class between instructors and students. • Surveys • Student surveys in CBI classes were used to elicit students' perceptions of how well the course was informed by the HPL framework and their reactions to various methods used during the semester. • The "Experiences in and Benefits from This Course" (EBC) survey, items that captured the features of the HPL Framework were selceted. • A Student Exit Survey was used to capture students' reaction to various instructional methods used in the course. • Finally, the results from end of course evaluation surveys used by the School of Engineering were used to compare equivalence of instructors as an initial control and to measure post-CBI changes of the challenge-based instructor.
Method • Knowledge-based questions • Twelve to twenty representative knowledge-based questions were selected for comparison by the instructors of BME 101 each fall. • Effect size (ES) was computed as the difference in mean score between the CBI and traditional groups divided by the pooled standard deviation for knowledge-based questions. • Questions were divided into two groups: more difficult and less difficult, depending upon whether the average of all student scores (both CBI and Control) on that question was less than or greater than the average of all student scores for all questions.
Results-Instruction practices They agreed that the CBI course focused on knowledge that is relevant to their future goals (questions 1, 5, 12, 16,1 7) They are motivated to do well (question 18), but probably no more than in a traditional class (questions 19, 20). They acknowledged the value of the assessment tools used in the course (questions 2,3,4) They recognized the importance of learnercentered (questions 3, 4, 8, 15) and the community-centered nature of the course (question 9)
Discussion • The traditional lecture-based approach is commonly accepted as the most efficient way to convey the large amount of information that students will need to become proficient in the subject matter. • However, results from the current study show that students in challenge-based courses can perform just as well as students in lecture-based courses on virtually all topics, and actually perform better at the end of the course on some of the more difficult knowledge-based questions. • Learner-centered activities in the classroom provide students with an approach to solving problems in situations where they do not have enough information at hand to do so. • By having students struggle with challenges, they become conditioned to ask appropriate questions and become familiar with where to find relevant answers. • Allowing more time in the classroom for discussion, reflection and appropriate formative assessment gives learners more opportunities to realize what they do and do not know, perhaps leading to a better understanding of the relevant concepts.
Discussion • The benefits to students' perceptions as learners and their development as professional engineers are important advantages of challenge-based instruction. • Students' viewpoints measured from survey data and end of semester student evaluations indicate that students value the challenge-based approach slightly more than the traditional lecture-based approach. • A possible explanation is that students who participated in the earlier surveys had only a short exposure to active learning activities, while CBI students in the current study were fully immersed in the HPL environment for the entire semester, and had more time to consider its benefits. • Why should an instructor make an effort to switch to a challengebased model of instruction? • At first glance the relative differences between CBI and traditional instruction appear small based on the average scores on knowledge-based questions • A closer look at the results shows that the difference between classes was greater when the comparison was focused on questions that require a higher degree of conceptual knowledge and integration of ideas necessary to solve a given problem. • The CBI approach provides learners with a solution procedure that can be carried beyond the course itself. • Finally, maintaining a consistent control for this study was difficult. • As time progressed, the control instructor was learning more about effective instructional practices including instructional innovations used by the CBI instructor.
Conclusions • In this study students exposed to taxonomy-based (traditional) and challenge-based approaches to instruction performed similarly on most knowledge-based assessments. • However, students in the challenge-based class appeared to have a better command of some of the more difficult concepts in the course, such as moments. • The motivation for using challenge-driven instruction is to encourage students to think through engineering problems before trying to solve them. • We provide real life challenges that put students in the position where they need to sort out for themselves what parts of the taxonomy are relevant to the problem at hand. • Students may find this approach more demanding at first, but we believe that this will better prepare them for the workplace and for life-long learning.