Session T1A AN ACTIVE LEARNING DESIGN PROJECT FOR A JUNIOR-LEVEL KINEMATICS AND DYNAMICS CLASS Jack Leifer1 Abstract This paper describes a design and modeling experience that was added to a junior-level, mechanical engineering class (Kinematics and Dynamics). Students were tasked to design, build, model, and demonstrate an apparatus that met the following criteria: (1) demonstrated one or more concepts developed in class; (2) had one or more attributes that could be varied; (3) took into account all parameters (intended and unintended) affecting the apparatus output, and (4) would be interesting to students 14 years of age and older. The last requirement ensured that the projects could be demonstrated meaningfully to high school groups visiting our campus. Students completed individual, post-project questionnaires, and reported that their understanding of concepts such as friction, impact, momentum, and projectile motion was enhanced as they constructed and tested their devices. Furthermore, most now understand that “real-world” problems often cannot be solved through the simple application of the analytical approaches presented in their textbooks. Index Terms Active learning, collaborative projects, dynamics, engineering mechanics, group projects.
INTRODUCTION The new ABET Engineering 2000 Outcomes require that graduates from ABET accredited programs have skills that include [1]: • an ability to function on multi-disciplinary teams; • an ability to design and conduct experiments, as well as to analyze and interpret data; and • an ability to communicate effectively. Prior to ABET 2000, these skills were most commonly emphasized in laboratory and design courses, where students were required to work in groups that produced both written reports and oral presentations. Under the new criteria, however, projects that encourage teamwork, experimentation, and communication are being added to courses traditionally offered in a pure lecture-oriented format, including Statics [2], and Kinematics and Dynamics [3] – [7]. These projects were shown to increase the understanding and retention of the course material by students, and also enhanced their problem-solving skills. This paper describes the development of another such group design and modeling experience, added to a junior-level Dynamics class at a new, off-campus engineering program offered by the University of Kentucky. 1
INSTITUTIONAL PROFILE In 1997, the University of Kentucky began offering coursework leading to Bachelor of Science degrees in Mechanical and Chemical Engineering at an “extended campus” facility in Paducah, Kentucky, located about 270 miles west of UK’s main campus in Lexington [8]. Although students are admitted to the Extended Campus Programs under the same criteria used for admission to the main campus, the demographics of the two student populations are quite different. The Paducah program serves an even mix of traditional (18-22 year old) and non-traditional (greater than 22 years old) students who all commute to campus, while the main campus is attended primarily by residential students of traditional college age. Currently, there are about 80 students majoring in mechanical engineering on the Paducah campus, and the number of students in a typical junior-level course rarely exceeds 20. The content of the programs in Paducah and Lexington is identical, however, the disparities in student body size and demographic profile between the two programs creates differences. For instance, the small number of students attending Paducah allow strong groups (or cliques) to form and endure as students enter the program and attend the same class sections together. In addition, the small number of Paducah faculty virtually ensures that they will have each student in more than one class, which engenders a great degree of student/faculty rapport and familiarity. The diversity of our students’ ages and experiences, as well as the strong student-student and student-faculty bonds that develop in small programs, must be taken into account when assigning group projects.
PROJECT DETAILS The project assigned in the Kinematics and Dynamics (EM 313) course offered at the UK/Paducah campus has evolved over the past two years. Dissatisfaction with student performance on the project in prior semesters (Fall 2000, Summer 2001) led to the modified project described herein. For the original project (adopted from a common boilerplate used in a number of engineering classes at UK, as well as other schools), each student in the class was asked to write a paper on a device or system that could be analyzed using one or more of the topics studied in EM 313. The assignment, due on the last day of class, included the following instructions: • Describe the system chosen for analysis (e.g. bicycle).
Jack Leifer, University of Kentucky, Department of Mechanical Engineering, PO Box 7380, Paducah, KY 42002
[email protected]
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Describe the relevant equations used to quantify the performance of the system (e.g., rotational kinematics equations that link the motion of the pedals and the wheels). Try to verify the validity of the textbook equations by taking measurements of and performing experiments on the system (e.g., an actual bicycle). If experiments and/or measurements cannot easily be performed, use published data and/or typical values to complete verification calculations. If the experimental data and the theoretically-expected results do not agree, determine a plausible explanation for the discrepancy.
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Many students simply did not know how to utilize numerical data to compare the performance of their system with analytical models. Students had trouble understanding the difference between ideal and real mechanical elements, and often expected the performance of the real systems to exactly match that predicted by the idealized textbook models.
Some of these problems could have been solved if the students had either sought out, or had been provided with, additional feedback on their projects prior to its final due • date. Such feedback could have been used by students, in “real-time” (closed-loop) fashion as they wrote their papers, to ensure that they were not headed down the wrong path. Extensive comments were included on the graded papers; The objectives of this project were the following: however, the late due date meant that only students who • Give students an appreciation of how specific material chose to pick up their papers after the semester was over had covered in class relates to the behavior of at least one the opportunity to read the instructor’s feedback. In well-known mechanical device or system. addition, this feedback was provided too late to help “close • Show students that the ideal textbook elements (e.g., the loop”, which could have eliminated many of the frictionless joints, linear/massless springs, rigid masses) problems present in the graded papers. are only approximations to the real elements appearing After looking at the students’ performance over the two in physical systems, and that effects from other energy semesters this project was assigned, a number of major domains (e.g., thermal, electric) may affect the dynamic changes were implemented for the Fall 2001 semester. The behavior of a system. changes were designed to preserve the previously outlined • Teach students how to collect relevant data on the objectives, while increasing the students’ probability of behavior of a physical device, or to find previously successfully fulfilling the project goals. In addition, the published data on device performance. project was restructured to support the new ABET 2000 • Enable students to determine whether the analytical objectives pertaining to teamwork, communication, and models presented in their textbook adequately model the experimentation. These changes included the following: behavior of their chosen “real-world” system. • The students were required to design, build and analyze • Provide students an opportunity to write about a a new mechanical apparatus, rather than simply technical topic, where equations, diagrams, and tables of performing measurements on a preexisting system or data are integrated into one cohesive report. obtaining performance data for devices to which they had no access. The process of designing and building a These projects were assigned individually, in an attempt dynamic system would require students to consider the to ensure that every student independently fulfilled all of the behavior of each individual system component, as well objectives described above. Each student was required to as how the selected components would behave and submit his/her choice of topic in advance to the course interact as elements of one cohesive system. instructor, so that he/she would have some prior feedback • Each apparatus was to be designed as an experiment pertaining to its suitability (e.g., topic is too broad, hard to that could communicate one or more of the dynamics obtain performance data, topic requires theory not covered in principles covered in class (e.g., conservation of energy, this course). conservation of momentum). The instructions provided Certain trends were noticed when analyzing the graded to each group read, “Choose one of the topics treated in papers: class, and develop a teaching aid that can be used for • Many students emphasized qualitative descriptions and demonstration purposes. The demonstration should be historical development of their chosen systems, and did understandable by students as young as 14 years old. not include any numerical performance data or other Your apparatus should provide a quantitative analysis. demonstration of the selected topic, which means that • Despite course instructor input, some students chose an indicator or measuring device must be included to systems that were too complex to be modeled using allow comparison of theoretically predicted to actual material covered in the course (e.g., inertial guidance performance. In addition, the apparatus must be system, aircraft take-off and landing behavior). adjustable to allow for different configurations and/or • Most students chose systems to which they had no values to be shown.” All performance parameters of access for experimentation. the apparatus had to be measurable, and any deviations from the expected (ideal) behavior had to be explained. 0-7803-7444-4/02/$17.00 © 2002 IEEE November 6 - 9, 2002, Boston, MA 32 nd ASEE/IEEE Frontiers in Education Conference T1A-14
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A feedback process was implemented by requiring that students work in groups. Feedback paths exist in both well-functioning and dysfunctional groups. In a wellfunctioning group, the consensus building that takes place during group meetings can be regarded as a form of closed-loop feedback, which serves to improve the quality of the project, and reduces the chance that things will proceed down the wrong path. In a dysfunctional group, disgruntled memb ers are likely to complain to the course instructor at an early stage. This enables appropriate instructor intervention (feedback) that can set a project back on course. Each apparatus was to be accompanied by a written report, and was to be demonstrated to the class on the last day of the semester. In addition, students were encouraged to demonstrate and explain their systems to attendees of UK/Paducah’s annual Engineering Day Open House held on February 23, 2002. Over 500 people of all ages attended this event.
GROUP FORMATION AND EVALUATION In order to increase the chance of having functional, successful groups, the course instructor organized the student groups using the following criteria: • Diversity of ability. Students were divided to ensure that the entire range of abilities present in the class was represented in each group. The instructor was able to take performance in previous classes into account, as he had taught many of the students in prior semesters. Both academic ability (measured by course grades) and design and construction ability (based on general knowledge of student background) was considered in forming the groups. • Age and experience. Students of different ages and experiences generally approach their work differently. At UK/Paducah, there is little casual interaction between nontraditional and traditional students, and students allowed to form groups on their own tend to gravitate towards others with similar backgrounds. Creating groups with members of diverse educational backgrounds and experiences, however, provides students an opportunity to learn from one another alternative approaches and points of view. • Cliques. In order to increase the opportunity for all group members to participate fully, members of previously established “cliques” or study groups were separated, wherever possible. This helped prevent a situation where non-clique members within a group containing an established clique would be excluded as “outsiders”. While small programs such as this one are likely to have a number of well-established cliques that go through the engineering curriculum together in lockstep, faculty are likely to be aware of their existence and should take appropriate action to prevent them from negatively affecting group projects.
Many instructors form student groups by using the results of standardized tests such as the Myers -Briggs Personality Type [9]. However, in a small program such as this one, the instructor felt that his prior knowledge of individual student work styles, as well as the small class size, would allow him to form successful groups without the use of such instruments. When students are confronted with collaborative group projects, they are often concerned that they will be penalized if one or more group members do not do their share of the work, as all group members are generally assigned the same grade for the project. Adapting a technique introduced to the author by M.D. May [10], this concern is addressed by requiring that students turn in a performance evaluation of all group members – including themselves – along with the final project. The students are prohibited from discussing the evaluations with each other, and privacy is maintained by having each student place his or her set of evaluations in a sealed envelope before they are submitted. This provides the instructor with insight regarding how the group functioned, and allows an individual’s grade to be adjusted by the instructor, if justified by the contents of the evaluations.
RESULTS AND DISCUSSION The Fall 2001 section of EM 313 contained a total of eight students. They were divided by the instructor into two groups of four, based on the criteria discussed in the previous section. Both groups initially chose to build devices that demonstrated the concept of Conservation of Energy; however, each took vastly different paths towards project completion. Trebuchet The first group decided to build a model trebuchet, which is a mass-actuated device used to propel projectiles over long distances (Figure 1). Trebuchets were used during Medieval times for military purposes, as a means of breaching the protective walls of castles or other such protective enclaves. One particular student came up with the idea of building a trebuchet before the project was assigned, and after convincing his group to go along with his idea, led them through the design and fabrication process. Although the device functioned well and can be used to demonstrate and validate many dynamics principles, the students ran out of time before they were able to perform a complete experimental analysis of the trebuchet’s performance for inclusion in the final paper. From the students’ written comments, however, it is apparent that they did connect the performance of the trebuchet to concepts covered in class: • “The way in which the various forces combined was not clear to me at first. I thought the sling force multiplied with that of the lever arm but as we worked with the trebuchet and through the equations, it became clear that
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they were additive forces. This made sense after working with the finished product.” “For me, it came together the last night when testing the weapon and working with the equations at the same time.” “(The project) reinforced topics covered in class... (it) put dynamics into a visual context for me. I could actually see the angular acceleration, the mass moment of intertia, the projectile motion, and so forth. “As for the (modeling), I knew that would be an extreme challenge but I didn’t worry about it as much as the other aspects... the real imperative issue for the team and myself was to make it work.”
FIGURE. 1 T REBUCHET. T HE COUNTERWEIGHT CAUSES THE SLING TO LAUNCH THE PROJECTILE ( WASHER). T HE PLYWOOD BASE IS CLAMPED DOWN TO PREVENT IT FROM SHIFTING AS THE PROJECTILE IS THROWN .
between the mass and the block, and were able to calculate the coefficient of friction between the block and the track by measuring the stopping distance of the block. Although frustrating, the students found that the repeated redesign/build/test cycles endured provided unique insight into the course material. They also learned something about the iterative nature of the design process, and about the importance of planning, as noted by their comments: • “With this type of project you have to build the apparatus in such a manner that you can account for everything that happens and then work the calculations from there. The main thing to consider is that you must know what (parameters) you want to find and then design the project in such a manner so that all other unknowns are eliminated.” • “... we don’t need to rush into construction, but need to work out some of the problem on paper first... (to) make sure that it is a plausible plan.” • “I don’t think I can emphasize enough how much the project helped me to better understand the concepts of Dynamics. It was really satisfying to build something... and then apply to it the equations out of the book.” • “My group built two projects before we got the third one to work. Just because the projects looked rather simple and easy to apply equations to, it doesn’t mean that (we could solve for all the unknowns).” • “Even on the final (design) we had things crop up that we were not expecting such as the static electricity that built up between the blocks and the track... if I had a chance to start over again the main thing I would have done would be to study the problem I was getting ready to tackle more.”
Friction Tester The second group initially wanted to build a device that utilized a “hotwheels” car and plastic racetrack to demonstrate the link among potential energy, kinetic energy, and normal acceleration, by observing the mo tion of the car as it traversed a vertical “loop-the-loop”. The group could not reconcile the car’s motion with the theoretical predictions, however, because they (1) did not know the coefficient of friction between the car and the track, (2) could not force the track into a circular path, and (3) found that the track was compliant, and deflected significantly as the car traveled through the loop. After consulting with the course instructor about the problems they were having with their initial device, the group went through two complete redesign/build/test cycles, and each time reduced the number of unmodeled parameters present in their system. Their final submission is pictured in Figure 2. Here, a mass is released from a known height, and collides with a block located on a track. Based on observations made during the impact, the students were able to calculate the coefficient of restitution
FIGURE. 2 FRICTION TESTER. MEASUREMENT OF STOPPING DISTANCE ALLOWS CALCULATION OF THE COEFFICIENT OF FRICTI ON BETWEEN THE BLOCK AND TRACK . MEASUREMENT OF MAXIMU M PENDULUM HEIGHT ATTAINEDAFTER IMPACT ALLOWS CALCULATION OF COEFFICIENT OF RESTITUTION.
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Session T1A Evaluation of Group Experience The students generally found that working in groups was a positive experience. They did report a number of frustrating aspects, however, that could have been avoided through careful, timely planning, as well as defining specific roles for each group member. Additional instructor intervention may have also been useful, as indicated in the following student comments: • “..in retrospect I think it would have been more efficient to run the group as a committee and have weekly meetings to discuss how things are going. This would keep everyone on track and motivated.” • “Group interactions were something that simply didn’t happen over the course of the assignment... I think the instructor on projects of this type would serve his students well by handing out guidelines on how to effectively organize a project of this type.” • “With four of us working together, it allowed us all to help each other understand the concepts a little better... there was always someone there to check...” • “By working in a larger group, I have a new understanding of the complication of dividing the work, and how hard it can be for everyone’s schedule to (arrange) collaboration.” • “While each person wanted to contribute to the overall project, there was not much effective coordination among the four of us.” • “Perhaps the partners should grade each other on the work they did, with that becoming a percentage of the overall project grade.” • “I think that every group needs a leader, but not a dictator... to keep the group on task.”
each device. Over the course of a one-hour period, about 20 secondary school students and their parents visited our area, where they were each treated to one-on-one demonstrations of the devices (Figure 3). This provided sufficient time to explain each device, and allowed the Dynamics students to field visitors’ questions and comments. In future years, it is envisioned that the exhibit will expand as more student projects are built and added to the collection. TABLE I MEAN RESULTS FROM STANDARDIZED STUDENT COURSE SURVEYS. 1.0 = STRONGLY DISAGREE; 4.0 = STRONGLY AGREE WITH STATEMENT Question Fall 2000 Fall 2001 Increased my ability to analyze 3.3 3.3 and evaluate Helped my ability to solve problems
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Gained a good understanding of the concepts and principles presented
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Overall value of the course (1.0 = 3.2 poor, 2.0 = fair, 3.0 = good, 4.0 = excellent)
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Course Evaluation Results Course evaluation scores from the Fall 2000 (individual project; 13 respondents) and Fall 2001 (group project; 7 respondents) sections are shown in Table I. A simple comparison of the results indicates that student satisfaction has increased with the introduction of the group project. Statistical significance of the results could not be ascertained, however, because of the small numbers of students involved. In addition, results of the Summer 2001 semester were not included because it was offered in a highly compressed, evening format that is very different from the typical Fall semester schedule. Demonstration of Projects Both the trebuchet and the friction tester were demonstrated at UK/Paducah’s Engineering Day, held on February 23, 2002. Because of the timing of the event, as well as other student committments, it was not possible to have every EM313 student present to run the demonstration. However, two students were available, which was enough to cover
FIGURE. 3 DYNAMICS STUDENT ANDY KALER DEMONSTRATES TH E TREBUCHET TO AN ENGINEERING DAY PARTICIPANT.
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Session T1A CONCLUSION AND RECOMMENDATIONS
ACKNOWLEDGMENT
In general, the introduction of group projects to Junior Dynamics at UK/Paducah has been successful. Student comments generally indicate that they felt the assignment was worthwhile and useful, and certain specific comments reinforce the premise that active learning through experimentation and design causes the students to internalize the concepts covered in the course. Further, they indicate that although all successfully demonstrated working devices, they learned that group work takes a great deal of planning and coordination. Some students also believe that early instructor guidance or intervention would have improved their group’s experience. As the project was generally well-received by the students, it will be included again in EM313 when it is offered in the Fall 2002 semester. However, based on student feedback, the following changes are planned: • More attention will be paid to ensuring that the groups are functioning smoothly. A short reference on “group dynamics” from an introductary engineering textbook [11] will be made available, and some class time will be used to review this material with the students. The instructor will require each group to designate a project leader at the outset. He will also suggest regular meetings, as well as the use of Gantt charts or other methods to ensure the group accomplishes its tasks in a timely manner. • Comparison of device performance to analytical models was not adequately accomplished by either group. It is possible that the students did not understand exactly what such verification entailed, so specific examples, using both the trebuchet and the friction tester, as well as other available devices, will be provided when the projects are initially assigned. The instructor will stress the importance of choosing projects that are both simple to construct and easy to characterize. • The projects will be assigned earlier, to reduce the endof-semester time crunch that students always seem to experience.
The participation of EM 313 students Boyd Caddell, Chris Dodson, Andrew Kaler, Chris Meyer, Justin Norris, Allyne Palmer, Steven Trimble, and Anthony Van Cura in this project is greatly appreciated.
REFERENCES [1]
ABET Engineering Criteria 2000. Available at http://www.abet.org
[2]
Palmer, M.A., Sandgren, E., Heinz, R.A., Chatterji, A., and Haas, T.W., “A Novel Approach for Teaching Statics”, Proceedings of the 28 th ASEE/IEEE Frontiers in Education Conference, Session S3E, Tempe, AZ, 11/98.
[3]
Yaeger, P.M., Marra, R.M., Costanzo, F., Gray, G.L., and Sathianathan, D., “Interactive Dynamics: Effects of Student-Centered Activities on Learning”, Proceedings of the 29th ASEE/IEEE Frontiers in Education Conference, 11a2-13, San Juan, PR, 11/99.
[4]
Pionke, C.D., Parso ns, J.R., Seat, J.E., Weber, F.E., and Yoder, D.C., “Integration of Statics and Particle Dynamics in a Hands-On ProjectOriented Environment”, Proceedings of the ASEE Annual Conference, Session 1368, Charlotte, NC, 6/99.
[5]
Costanzo, F., and Gray, G.L., “Collaborative Learning in Undergraduate Dynamics Courses: Some Examples”, Proceedings of the ASEE Annual Conference, Session 3268, Charlotte, NC, 6/99.
[6]
Yaeger, P.M., Marra, R.M., Gray, G.L., and Costanzo, F., “Assessing New Ways of Teaching Dynamics: An Ongoin g Program to Improve Teaching, Learning , and Assessment”, Proceedings of the ASEE Annual Conference, Session 3530, Charlotte, NC, 6/99.
[7]
Haik, Y., “Design-Based Engineering Mechanics”, Proceedings of the ASEE Annual Conference, Session 2625, Charlotte, NC, 6/99.
[8]
Capece, V.R., Murphy, W.E., Lineberry, G.T., and Lykins, B.L., “Development of an Extended Campus Mechanical Engineering Program”, Proceedings of the ASEE Annual Conference, Session 1566, St. Louis, MO, 6/2000.
[9]
Dyrud, M.A., “Getting a Grip on Groups”, Proceedings of the ASEE Annual Conference, Session 3230, Charlotte, NC, 6/99.
[10] May, M.D., University of South Carolina – Aiken, personal communication. [11] Horenstein, M.N., Engineering Design, Prentice-Hall ESource Introduction to Engineering Series, 1999.
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