By: Francois Marshall
One of the greatest difficulties that students confront when they learn physics is to understand the abstract concepts that describe physical phenomena. From experience in working as a TA for first-year astronomy and electromagnetism courses for non-physics students, I have found that it is fruitful to emphasize interaction with students to reinforce concepts of the course material. The themes of pedagogic-content knowledge (PCK) and hands-on activities are crucial to helping students integrate the knowledge that they acquire into their thought process for current and future problems that they must solve in these courses [3]. Therefore, these active-learning strategies help students to understand important threshold concepts, and thus develop their independent understanding of the course material [3].
Learner-centred teaching is a pedagogic method in which the students are central to the teaching process [3]. Their short-term retention of the course material is significantly improved when they are actively participating in observation sessions or in experiments than when they are listening to tutorial lectures, and this agrees with the hypothesis of Bryant et al [1]. Students must have the incentive to adapt to a new manner of thinking, and this is encouraged via the use of hands-on activities, as well as working in groups [3]. This is student engagement, and the most important role of the TA is to offer the students insight into using the right approaches of solution, so that they can integrate these ideas into their current methods [3]. The goal is to enable the students to have their own appreciation of the subject matter and an independent manner of solving problems [3]. In this way, they are better prepared for assignments and exams, as they can refer back to results or examples that they have seen directly or verified for themselves. Once students have developed an independent understanding of how to work out the driving mechanism for a physical phenomenon, they have undergone a transformative event for a threshold concept, which they will likely integrate into their thought process for future problems [3]. They begin to understand how independent core concepts relate to one another [3].
PHYS 1901 is the fall-term astronomy course at Carleton, and is primarily intended for students outside the discipline of physics. Many of these students are from backgrounds with limited training in the application of the scientific method. One of the goals of this course is to demonstrate a real application of the scientific method, so that students can learn how to determine the driving mechanisms of astronomical phenomena based on observational data. For those students, the scientific method is a threshold concept. Observation sessions form an excellent bridge between the course lectures and the way that each student thinks about the material. This is because the TA is showing them celestial objects through an eyepiece, and is explaining to them that what they are looking at is an example of the physics that they learnt in the course. From experience of attending star parties, I have noticed that volunteers of the Royal Astronomical Society of Canada advocate the approach of inquiry-based teaching for members of the public [2]. As an example of this approach, the student gains an independent appreciation of the celestial object when s/he understands the threshold concept of a dynamic night sky. Showing the students Jupiter on different nights and asking them to look for where the certain Galilean moons are located helps them to understand Galileo’s observations during the Renaissance because they notice that the locations have changed a week later. They now see a dynamic situation unfolding in the eyepiece, where before they could only see a static image. In the midterm exam, the results of the question about Galileo’s observations of the Jovian moons, and his conclusions regarding the heliocentric model, were answered considerably better than some of the other questions. The sessions reinforced the key concepts of a dynamic sky, and the results reflected favuorably on the inquiry-based approach. From student feedback during the sessions, they made it clear that they could start to see how the physics was useful for describing the object in the eyepiece.
To accomplish the task of making the night sky more real, it was most useful to concentrate on recurring themes, such as sizes, distances, and references to known terrestrial phenomena. Students are more engaged if they realize that the eyepiece image of a distant nebula is a hundred-year old antique. Then they have a way of recalling facts about the speed of light, because it is this limitation on information transport that results in delayed images. Therefore, in future assignments, students could remember that light was composed of particles that travel with a constant speed.
Completing office hours in this course required a level of patience in order to let the students understand the assignment problems in a manner that they could make sense of. Without a strong background in physics or advanced mathematics, it is often difficult to work with reference frames, so this was the most important threshold concept that students had to deal with in the problem sets. There was one particular problem that was difficult for the majority. Three-dimensional problems are a common stumbling block in introductory astronomy courses, where often two diagrams are required to solve the problem correctly, and the student needs to understand one in terms of the other [2]. The problem was to determine the locations of celestial objects and trajectories according to the observer reference frame for different times of the year. The key to opening the gateway of this threshold concept was to show the students a sequential description of the processes that dictated annual celestial dynamics. Thus, each step in the explanation moved the process forward in time, and this strategy allowed for student engagement between the steps; they could describe the process in their own words to ensure that they could follow. This student-centred approach helped them to determine a strategy for envisaging dynamic systems based on static descriptions. In other words, a transient process could be understood from a static setup of initial conditions when the time is expressed as an ordered sequence of descriptions.
The astronomy course involved teaching students the basic thought process for scientific study, whereas in the winter-term engineering electromagnetism course, PHYS 1004, the students had some background in physics and advanced mathematics. However, the key threshold concepts were similar to those of the astronomy course. In particular, students had the most difficulty with physical systems, in making the transition from static descriptions to dynamic processes. Having observed the difficulties and the successes that students had in the lab section, the results from Bryant et al that hands-on activities are most beneficial to immediate retention of course material again seems to withhold [1].
In the laboratory, students are asked to solve complex problems involving the dynamics of circuits. In this case, PCK is aiding students in following the instructions from the lab manual independently, by understanding the physics via a series of analogies. When students become confused, it is most often because they can only interpret the instructions as a rigid list of activities; they do not see the effects of connecting certain wires or circuit components in particular configurations. The best way to aid students in overcoming this threshold concept was to describe the electron transport through the wires as the way that water is guided through tunnels. Many of the rules in electromagnetism are almost identical to those of fluid mechanics, so students better retain the rules for circuit-buildings once they have begun thinking in this manner. Their retention of material in the following tutorials was much improved because the material in these parts of the course involved the flow of current in circuit systems; thus, like with any threshold concept, the students were able to integrate these views of the circuit with the diagrams they had to make when they were solving problems. Teaching by analogy is useful when teaching mathematically-oriented subjects to engineers because they have a strong understanding of macroscopic physical phenomena like stress and strain, or resonance [1]; the macroscopic analogies are an efficient tool to open to them the conceptual boundaries presented by the microscopic world.
Finally, active learning worked better when students were asked to work in teams of two during experiments than when they had to work in larger groups to solve tutorial problems. Many individual ideas are produced at the table during tutorial sessions, so the tendency to develop an individual approach was diminished. If learner-centred teaching is to be the primary goal of pedagogic approach, it may be useful to gradually migrate students from working in groups to working in pairs later in the semester, so that they can be better prepared to solve problems individually come the final exam.
References:
[1] Bryant, Aric et al, “The Role of Active Learning through Laboratory Experimentation Pertaining to Memory Retention in First-Year Engineering Programs”, Binghamton University, IEEE, 2009.
[2] “Tips on Teaching Astronomy”, The Canadian Astronomical Society, http://www.cascaeducation.ca/files/teachers_tips.html
[3] Zepke, Nick, “Threshold concepts and student engagement: Revisiting pedagogical content knowledge”, Active Learning in Higher Education, Massey University, New Zealand, 2013.