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Canine hip forces: The ups and downs of project-based learning of static equilibrium

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2017 ASEE Annual Conference & Exposition


Columbus, Ohio

Publication Date

June 24, 2017

Start Date

June 24, 2017

End Date

June 28, 2017

Conference Session

First- and Second-year Design and Professional Development in BME

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Kristen Billiar Worcester Polytechnic Institute

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Kris Billiar is Professor and Head of Biomedical Engineering at Worcester Polytechnic Institute. He earned a B.S. in Mechanical Engineering at Cornell and an M.S.E. and Ph.D. in Bioengineering at the University of Pennsylvania. His current research interests are soft tissue mechanics and mechanobiology. Dr. Billiar is a Fellow of both ASME and AIMBE and a member of ASEE.

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Kaitlyn A Marengo Worcester Polytechnic Institute

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Kaitlyn Marengo is a graduate student pursuing a Master’s of Science in Biomedical Engineering at Worcester Polytechnic Institute. Originally from Dudley, MA, she obtained a Bachelor’s Degree in Biomedical Engineering in 2015 from WPI. As a graduate student she has served as a Teaching Assistant to undergraduate level biomedical engineering courses as well as pursued a research project in the Myocardial Regeneration Laboratory focusing on improving stem cell delivery methods into the heart following a myocardial infarction, or heart attack.

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Sophomore-level engineering students are often adept at solving highly defined problems such as the forces in a simple bridge, but falter when asked to solve a more open-ended problem and describe the concepts involved. Further, many students, especially female, are not intrinsically motivated to analyze bridges and cranes and are more inspired by problems closer to their own experiences. To address the need to motivate student interest and increase their conceptual understanding of static equilibrium and ability to solve authentic, unconstrained problems, we developed and implemented an open-ended project in our introductory biomechanics course.

To engage the interest of the students, they were told that veterinarians are reporting higher-than-acceptable cracking of the plastic portion of the acetabular cups in a total hip replacement products causing undue pain and suffering to many dogs, especially large breeds. Seventy-five students, mostly sophomore biomedical engineers, were randomly assigned into three-person teams and challenged to analyze the mechanics of the canine hip to determine the force that the femoral head (ball) applies to the acetabular cup and, if possible, to come up with a better design or alternative solution. The project assignment, a two-page team report with appendices containing individual students’ diagrams and calculations, took the place of the first two homework assignments from the previous offering of the course. The project was assessed using a detailed rubric that was provided to the students with the assignment. A quiz was administered to assess the students’ ability to perform basic static analyses and describe static equilibrium concepts in writing; the question type and difficulty were equivalent to those on the quiz in the previous course offering. Results from the two offerings were compared using unpaired t-tests with p<0.05 considered significant.

The average score of the projects were higher than those of the homeworks in the previous offering (99% vs. 89%, p<0.001). This result was to be expected since the students were encouraged to utilize the rubric to assess their own work while completing the project, and they could ask the instructor (1st author) and teaching assistant (2nd author) for specific feedback before handing in the reports; further, they could earn up to 10 points extra credit for offering additional impact demonstrating an entrepreneurial mindset. In contrast, the scores on question 1 (forces and moments) and question 2 (rotational static equilibrium) from the quiz were significantly lower for the students completing the project compared to those completing the homeworks in the previous offering (Q1: 69% vs. 92%, p<0.001; Q2 59% vs. 83%, p<0.001). Interestingly, the students did significantly better in describing the concepts of static analysis following the project compared to doing homeworks (Q1: 95% vs. 72%, p<0.001). Over 75% of the teams received extra credit for demonstrating an entrepreneurial mindset.

These results indicate that spending time solving problems requiring analysis of multiple sources and establishing their own constraints rather than doing multiple highly defined problems similar to those given as a standard assessment yields lower performance solving this type of problem. However, our findings suggest that even limited project-based learning can have a positive impact on conceptual understanding (or at least the students’ ability to describe the concepts in writing).

Billiar, K., & Marengo, K. A. (2017, June), Canine hip forces: The ups and downs of project-based learning of static equilibrium Paper presented at 2017 ASEE Annual Conference & Exposition, Columbus, Ohio. 10.18260/1-2--28006

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