Practical School Experiments with the Centre of Mass of Bodies

  • Robert Repnik Faculty of natural sciences and mathematics
  • Milan Ambrožič Faculty of natural sciences and mathematics, University of Maribor
Keywords: centre of mass, practical school experiment, nature-science competences


The concept of the centre of mass of a rigid body as a virtual point where the weight force acts is not easy to understand without a number of supporting school experiments. In school practice, however, experiments on
this topic are often limited to a few of the simplest cases in which a simple flat body, such as a triangle or rectangle, is hung in two or mostly three directions to show where the corresponding plumb lines intersect. Typically, simple wooden bodies are used, on which the plumb lines are already drawn through the centre of mass. However, such experiments can be boring for students and are probably insufficient to illuminate all aspects of the topic. Furthermore, if the experiments are only demonstrated by the teacher rather than being performed in groups, the opportunity to train students’ skills and develop nature-science competences is missed. We therefore prepared and performed a series of group experiments in logical sequence for students of the 8th and 9th grades of primary school, so that their full active participation was invoked. The experience with such an experiment setup with very simple equipment, together with the open discussion of results, increased pupil motivation for physics and perhaps also improved understanding of some physics problems regarding the centre of mass, even for younger students. 


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Ambrus, A. (2014). Teaching mathematical problem-solving with the brain in mind: How can opening
a closed problem help? CEPS Journal, 4(2), 105–120.

DeBoer, G. E. (1991). A history of ideas in science education: Implications for practice. New York, NY:
Teachers College Press.

Fleming, N. D. (1995). I’m different; not dumb. Modes of presentation (VARK) in the tertiary classroom.
In A. Zelmer (Ed.), Research and development in higher education. Proceedings of the 1995 annual conference of the higher education and research development society of Australasia (HERDSA), Volume 18 (pp. 308–313).

Flick, L. B., & Lederman, N. G. (2006). Scientific inquiry and the nature of science: Implications for
teaching, learning and teacher education. Netherlands: Springer.

Gabel, D. (2003). Enhancing the conceptual understanding of science. Educational Horizons, 81(2),

Jarvis, T., Pell, A., & Hingley, P. (2011). Variations in primary teachers’ responses and development
during three major science in-service programmes. CEPS Journal, 1(1), 67–92.

Jones, L. L., MacArthur, J. R., & Akaygün, S. (2011). Using technology to engage preservice elementary
teachers in learning about scientific inquiry. CEPS Journal, 1(1), 113–131.

Kariž Merhar, V. (2008). Konstruktivistični pristop k pouku fizikalnih vsebin – nihanje in valovanje [A
constructivist approach in teaching physics topics: Oscillations and waves]. Unpublished Doctoral
dissertation. Ljubljana: University of Ljubljana, Faculty of Education.

Kline, J. (2010). Konstruktivistični pristop pri poučevanju fizikalnih vsebin – tlak in vzgon [A constructivist
approach in teaching physics topics: Pressure and buoyancy]. Bachelor thesis. Maribor: University
of Maribor, Faculty of Natural Sciences and Mathematics, Department of Physics.

Marentič Požarnik, B. (2004). Konstruktivizem v šoli in izobraževanje učiteljev [Constructivism in
school and teacher education]. Ljubljana: Centre for Pedagogical Education of the Faculty of Arts.

Minner, D. D., Levy, A. J., & Century, J. (2010). Inquiry-based science instruction – what is it and what
does it matter? Results from a research synthesis years 1984 to 2002. Journal of Research in Science Teaching, 47(4), 474–496.

Newman, W. J., Abell, S. K., Hubbard, P. D., McDonald, J., Otaala, J., & Martini, M. (2004). Dilemmas
of teaching inquiry in elementary science methods. Journal of Science Teacher Education, 15(4), 257–279.

Oblinger, D. G., & Oblinger, J. L. (Eds.) (2005). Educating the net generation, Educause. Retrieved from

Osborne, J., & Dillon, J. (2008). Science education in Europe: Critical reflections. London, UK: Kings

Pell, A., & Jarvis, T. (2001). Developing attitude to science scales for use with children of ages from five
to eleven years. International Journal in Science Education, 23(8), 847–862.

Plut Pregelj, L. (2008). Ali so konstruktivistične teorije učenja in znanja lahko osnova za sodoben pouk?
[Can the constructivist theories of learning and knowledge be the basis for modern education?]. Sodobna
pedagogika, 59(4), 14–27.

Potočnik, K. (2004). Konstruktivistični pristop pri pouku naravoslovja [A constructivist approach to
teaching natural sciences]. Bachelor thesis. Maribor: University of Maribor, Faculty of Education.

Solkan primary school (2017). Fizika je zakon [Physics rules]. Retrieved from http://sola-solkan.splet.

Šimenc, M. (2008). The status of the subject in the classroom community of inquiry. Theory and Research
in Education, 6(3), 232–336.

UNESCO Principal Regional Office for Asia and the Pacific (1991). Science curriculum for meeting real-
-life needs of young learners. Bangkok: UNESCO.