An assignment was developed in which students operate and make measurements of an elementary machine (bolt cutter) in order to produce a force analysis. The assignment supports sophomore studies in statics and is intended to contextualize the images and diagrams of certain artifacts presented for analysis in the textbook. The assignment is cast as a reverse engineering case study in which the student takes the role of an engineer that is participating in a benchmarking exercise of competitor products. Such a benchmarking exercise would typically require an engineer to handle multiple tools and to apply them to their intended use while considering various aspects of their operation and making comparisons in addition to making measurements and performing analyses. In this way, students performing the assignment are provided with a guided hands-on experience with hand tool operation that is intended to provide a richer experience than may be achieved in a tool operation and safety training session.
The development of this assignment was motivated by the authors observation that textbook problems associated within the Frames and Machines topic focus on heavy equipment and hand tools while students in the author’s program have limited experience with either. When informally questioned about how the extension of a hydraulic cylinder would affect the orientation of an excavator bucket students demonstrated a lack of ability to anticipate how the bucket would move (i.e. what point the bucket would pivot around), and how a hydraulic cylinder worked (i.e, that it extends and retracts). Likewise, with hand tools based on designs more complex that simple levers, students were unlikely to “see” how a locking pliers worked or how a bolt cutter makes use of a compound lever to develop a large mechanical advantage. The author considered that students lack of understanding of the artifacts being analyzed might contribute to their apparent problems performing the analyses. In the case of students that achieved some success, the author was concerned that students lack of exposure to “real” machines was limiting their understanding of the analyses they produced. The assignment was developed with the intent of providing context for the concepts communicated via direct instruction. As such, the assignment can be seen as leveraging “situated cognition”, a cognitive theory that suggests that information without context or with weak context is not knowledge.
This paper will describe the assignment to a level of detail that will support transferability. Details will include the assignment itself, materials required (including vendors and part numbers), a model of an appropriate student response, and an instructor tool that provides results for a general case. Student responses to the assignment which were recorded as part of student course evaluations will be shared and discussed.
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