PRACTICAL EXERCISES IN UNIVERSITY MECHANICS
In the present study, four practical exercises were introduced in a university-level mechanics course, in order to provide students with shared, personal, embodied experiences of physical phenomena in relation to the taught content. The practical exercises were performed during 10-15 minutes with subsequent discussion in random groups of 3-4 students during recitation sessions. Two of the exercises involved physically experiencing the reduced force of raising a 5 kg weight with a rope and a system of pulleys compared to with a rope alone, and finding the centre of mass of an object by holding under the object with ones hands and moving the hands toward one another. Video analysis of selected episodes of students’ interaction with the exercises reveals how they coordinated gestures and spoken language in expressing their conceptual understanding of the phenomena. In a subsequent group interview, participant physics teacher students expressed that the exercises were useful for feeling physically what they had previously only calculated. Apart from grounding conceptual understanding in physical experiences, the course evaluation shows that participation in random small groups led to increased communication among students that did not know each other before, thereby contributing to the development of a learning community.
Keywords: practical exercises; university physics; embodied experience
INTRODUCTION
There is an increasing awareness that traditional teaching approaches in university physics, such as one-way communication in lectures, recitation session with algorithmic problem solving, and expository laboratory work, are not effective in influencing students’ conceptual understanding of the taught topics (e.g. Knight, 2002). Therefore, physics teachers try to establish more student-active teaching approaches, where students engage in doing and talking physics with one another (Lemke, 1982). Furthermore, Knight (2002) recommends moving focus from mathematical abstractions to providing students with shared, concrete experiences of physical phenomena.
Our experience is that even engineering students often do not have the practical experience of mechanics or electronics that we might assume when they come to our courses. Airey and Linder (2009) describe the case of a university student that does not know what a transformer is, and is subsequently lost when the lecturer quickly moves over to mathematical formalism. Similarly, if a student does not know what a wrench is, this is not likely to be a useful starting point for an introduction of the torque concept. The present study is a case of introducing short practical exercises in a university-level course in mechanics, in order to provide students with personal experiences of physical phenomena in relation to the taught content. The overall aim of the study was to investigate the utility of practical exercises in university-level mechanics.
METHODS
The study was conducted in relation to a university course in mechanics for physics, engineering, and physics teacher students, in all about 120 participants. The response system Learning Catalytics (Schell, et al., 2013) is used in lectures in order to increase student interaction and provide prompt feedback. Courses with a focus on laboratory activities and measurement with written lab reports are required prior to the mechanics course, but the course itself has historically had a theoretical focus on conceptual understanding and algebraic problem solving. We identified a need to ground the theory of mechanics in students’ practical, embodied experiences (Amin, et al., 2015; Bruun & Christiansen, 2016), but without introducing traditional laboratory sessions.
We aspired to give students the opportunity to interact with mechanical devices and develop embodied experiences of the phenomena. Therefore, we developed four practical exercises, which students were asked to perform in random groups of 3-4 students during 10-15 minutes one after another during recitation sessions.
In line with Knight’s (2002) notion of experiential labs, they were asked to predict, observe and explain (POE, White & Gunstone, 1992) what happens in relation to a physical phenomenon qualitatively. In addition, adhering to Bernhard’s (2010) conceptual labs, students were encouraged to discuss what they had experienced by answering a set of conceptual questions in relation to the exercises. The exercises involved:
Experiencing the lower force of pulling up a 5 kg weight by a rope with a system of two pulleys, compared to a rope without pulleys (Figure 1a).
Practically establishing the centre of mass of an object by holding the hands under the object and moving them toward one another (performed after a lecture demonstration that the two parts on both sides of the centre of mass of a broom have different masses, Figure 1b).
Observing the changing normal force by standing on a bathroom scale in a lift, as it starts, moves at constant velocity, and comes to a stop.
The resulting pulling force on a dynamometer of a suspended weight and a horizontal force acting on the weight.
In the lectures after the recitation sessions, the lecturer connected to the practical exercises by giving multiple- choice questions in the response system, in order to give feedback to the students and evaluate the usefulness of the exercises. In addition, the students were given individual examining tasks in relation to the practical exercises that were generated algorithmically with the system Mastering Engineering (Pearson, 2019).
Data were collected by video observation (Derry et al., 2010) of the majority of the groups’ work with the practical exercises, audio recording of interviews with some of the physics teacher students on their impressions of the exercises after the course, results from the multiple-choice questions and individual tasks, and written course evaluations from about 80 of the students. Video clips that show how students’ conceptual understanding is supported by their embodied experiences, through physical engagement with the physical apparatus or enactment of phenomena through gestures (Goodwin, 2003), were strategically selected for further analysis.
RESULTS
The course evaluation and interviews with teacher students show that that the students in general enjoyed the practical exercises and found them useful in providing personal, physical experiences in relation to the theoretical course content. Of the four exercises, experiencing a system of pulleys and finding the centre of mass were seen as more engaging than the other two, which aligned with our impression as researchers after having observed the exercises. Therefore our analysis focuses on these two exercises.
Figure 1. The lecturer demonstrates pulling up a 5 kg weight with and without a system of pulleys (1a); The lecturer has divided a broom at the centre of mass, preparing to weigh the two parts (1b); A student enacts her embodied understanding of torque equilibrium of a pulley (1c); A student finds the centre of mass of a measuring stick by moving his hands towards one another (1d).
In Figure 1c, a student explains to her three group mates what she calls “the law of pulleys”, that a force pulling a pulley counter clockwise has to be counteracted by an equal clockwise force for equilibrium, when predicting the forces needed to pull up the weight. Her understanding of pulleys is enacted by her gestures, in coordination with an oral explanation (Roth, 2000). In general, the students were excited that the force needed to pull up the weight by their hands with and without a system of pulleys felt so different. In the subsequent interview, the teacher students commented on the activity. Pete: “Yes, it was good to get a feel for it. You’ve done calculations on pulleys, but you don’t quite believe it!” Charlie: “No, can it really be like this…? That I pull here, and I can lift however much I like, really… is that true…? And it really is!”
In the activity of finding the centre of mass, the students engaged with asymmetric objects, which has been found problematic among students in previous research, such as students’ balancing of baseball bats (Ortiz et
1a 1b 1c 1d
al., 2005). In addition to focusing on the centre of mass, many of the groups attended to the fact that when moving the hands towards the balancing point, typically only one hand at a time moves relative to the suspended object (Figure 1d), which led to a discussion of the difference between static and dynamic friction between two surfaces.
DISCUSSION AND CONCLUSION
Overall, we found the initiative of introducing practical exercises in a predominantly theoretical mechanics course worthwhile. The students were provided the opportunity to connect the taught content to personal, embodied experiences of the studied phenomena in line with what we had planned for. Although one or two of the students expressed that the exercises disrupted the recitation sessions in the course evaluation, most of them saw good value in taking part in them. Apart from learning the content, some of the students experienced that this brief 10-15 minute interaction with subsequent discussion in random groups led to different communication patterns in the class overall, where they got to talk to students they did not know before. In this way, the exercises contributed to developing a learning community (Kim et al., 2014). Going forward, we intend to keep the format of practical exercises in the course, but maybe replace the ones that were less engaging. We also plan to introduce practical exercises in a course in modern physics.
REFERENCES
Airey, J., & Linder, C. (2009). A disciplinary discourse perspective on university science learning: Achieving fluency in a critical constellation of modes. Journal of Research in Science Teaching, 46(1), 27-49.
Amin, T. G., Jeppsson, F., & Haglund, J. (2015). Conceptual metaphor and embodied cognition in science learning:
Introduction to special issue. International Journal of Science Education, 37(5-6), 745-758.
Bernhard, J. (2010). Insightful learning in the laboratory: Some experiences from 10 years of designing and using conceptual labs. European Journal of Engineering Education, 35(3), 271-287.
Bruun, J., & Christiansen, F. V. (2016). Kinaesthetic activities in physics instruction: Image schematic justification and design based on didactic situations. Nordic Studies in Mathematics Education, 12(1), 56-72.
Derry, S. J., Pea, R. D., Barron, B., Engle, R. A., Erickson, F., Goldman, R., . . . Sherin, B. L. (2010). Conducting video research in the learning sciences: Guidance on selection, analysis, technology, and ethics. Journal of the Learning Sciences, 19(1), 3-53.
Goodwin, C. (2003). The body in action. In J. Coupland & R. Gwyn (Eds.), Discourse, the body, and identity (pp. 19- 42). London, UK: Palgrave Macmillan UK.
Kim, M. K., Kim, S. M., Khera, O., & Getman, J. (2014). The experience of three flipped classrooms in an urban university: an exploration of design principles. The Internet and Higher Education, 22(July), 37-50.
Knight, R. D. (2002). Five easy lessons: strategies for successful physics teaching. San Francisco, CA: Addison Wesley.
Lemke, J. L. (1982). Talking physics. Physics Education, 17(6), 263-267.
Ortiz, L. G., Heron, P. R. L., & Shaffer, P. S. (2005). Student understanding of static equilibrium: Predicting and accounting for balancing. American Journal of Physics, 73(6), 545-553.
Pearson. (2019). Mastering Engineering. Downloaded 2019-01-27 from www.pearsonmylabandmastering.com.
Roth, W.-M. (2000). From gesture to scientific language. Journal of Pragmatics, 32(11), 1683-1714.
Schell, J., Lukoff, B., & Mazur, E. (2013). Catalyzing learner engagement using cutting-edge classroom response systems in higher education. In C. Wankel & P. Blessinger (Eds.), Increasing student engagement and retention using classroom technologies: Classroom response systems and mediated discourse technologies (pp. 233-261).
Bingley, UK: Emerald Group Publishing Limited.
White, R., & Gunstone, R. (1992). Probing understanding. London, UK: The Falmer Press.
