Anna De Ambrosis

How to teach friction: Experiments and models

Students generally have difficulty understanding friction and its associated phenomena. High school and introductory college-level physics courses usually do not give the topic the attention it deserves. We have designed a sequence for teaching about friction between solids based on a didactic reconstruction of the relevant physics, as well as research findings about student conceptions. The sequence begins with demonstrations that illustrate different types of friction. Experiments are subsequently performed to motivate students to obtain quantitative relations in the form of phenomenological laws. To help students understand the mechanisms producing friction, models illustrating the processes taking place on the surface of bodies in contact are proposed.

Studying the physical basis of global warming: thermal effects of the interaction between radiation and matter and greenhouse effect

We present a teaching module dealing with the thermal effects of interaction between radiation and matter, the infrared emission of bodies and the greenhouse effect devoted to university level and teacher education. The module stresses the dependence of the optical properties of materials (transparency, absorptivity and emissivity) on radiation frequency, as a result of interaction between matter and radiation. Multiple experiences are suggested to favour a progressive construction of knowledge on the physical aspects necessary to understand the greenhouse effect and global warming. Some results obtained with university students are briefly reported.

A Three‐Dimensional Approach and Open Source Structure for the Design and Experimentation of Teaching‐Learning Sequences: The case of friction

We have developed a teaching‐learning sequence (TLS) on friction based on a preliminary study involving three dimensions: an analysis of didactic research on the topic, an overview of usual approaches, and a critical analysis of the subject, considered also in its historical development. We found that mostly the usual presentations do not take into account the complexity of friction as it emerges from scientific research, may reinforce some inaccurate students’ conceptions, and favour a limited vision of friction phenomena. The TLS we propose begins by considering a wide range of friction phenomena to favour an initial motivation and a broader view of the topic and then develops a path of interrelated observations, experiments, and theoretical aspects. It proposes the use of structural models, involving visual representations and stimulating intuition, aimed at helping students build mental models of friction mechanisms. To facilitate the reproducibility in school contexts, the sequence is designed as an open source structure, with a core of contents, conceptual correlations and methodological choices, and a cloud of elements that can be re‐designed by teachers. The sequence has been tested in teacher education and in upper secondary school, and has shown positive results in overcoming student difficulties and stimulating richer reasoning based on the structural models we suggested. The proposed path has modified the teachers’ view of the topic, producing a motivation to change their traditional presentations. The open structure of the sequence has facilitated its implementation by teachers in school in coherence with the rationale of the proposal.

Investigating the role of sliding friction in rolling motion: a teaching sequence based on experiments and simulations

We designed a teaching–learning sequence on rolling motion, rooted in previous research about student conceptions, and proposing an educational reconstruction strongly centred on the role of friction in different cases of rolling. A series of experiments based on video analysis is used to highlight selected key concepts and to motivate students in their exploration of the topic; and interactive simulations, which can be modified on the fly by students to model different physical situations, are used to stimulate autonomous investigation in enquiry activities. The activity sequence was designed for students on introductory physics courses and was tested with a group of student teachers. Comparisons between pre- and post-tests, and between our results and those reported in the literature, indicate that students’ understanding of rolling motion improved markedly and some typical difficulties were overcome.

Magnetic damping: Integrating experimental and theoretical analysis

We discuss a sequence of experiments aimed at exploring electromagnetic induction phenomena and energy dissipation due to magnetic friction forces. We analyze the motion of a moving conductor as it passes between the poles of a permanent magnet. Motion and current-voltage sensors allow real time measurements of the position, velocity, and induced voltage. The analysis and interpretation of the results helps students construct and verify the theoretical model describing magnetic damping.

Understanding first-year students’ curiosity and interest about physics—lessons learned from the HOPE project

This paper focuses on results of an interview based survey of first-year university physics students, carried out within the EU Horizons in Physics Education (HOPE) project (http://hopenetwork.eu/). 94 interviews conducted in 13 universities have been analyzed to investigate the factors that inspire young people to study physics. In particular, the main motivational factor, which was proven to consist of personal interest and curiosity, was unfolded into different categories and detailed interest profiles were produced. The results are arguably useful to help academic curriculum developers and teaching personnel in physics departments to provide guidance to students in developing and focusing their interest towards specific sub-fields and/or to design targeted recruitment and outreach initiatives.

Pre-service teachers' approaches to a historical problem in mechanics

In this paper we report on an activity sequence with a group of 29 pre-service physics teachers based on the reconstruction and analysis of a thought experiment that was crucial for Huygens’ derivation of the formula for the centre of oscillation of a physical pendulum. The sequence starts with student teachers approaching the historical problem and culminates in a guided inquiry activity in a video-based laboratory (VBL) setting using Tracker software. We collected data before, during and after the experimental activity by means of written questions, oral discussions and final reports. These documents provide insights into students’ initial and evolving conceptions, as well as their attitudes towards the activity. The analysis of data allows us to uncover and focus on relevant difficulties for future teachers in mastering the concepts of centre of mass and conservation of energy. Moreover, we find indications that the VBL environment makes a positive contribution by stimulating and improving students’ modelling abilities. In particular, we find a sharp increase in the percentage of students capable of producing coherent explanations and physical analyses for the Huygens’ pendulum system after the Tracker activity.

Reconstruction of Huygens' gedanken experiment and measurements based on video analysis tools

In this paper we describe the practical realization and the analysis of a thought experiment devised by Christiaan Huygens, which was pivotal in his derivation of the formula for the radius of gyration of a compound pendulum. Measurements are realized by recording the experiment with a digital camera, and using a video analysis and modelling software tool to process and extract information from the acquired videos. Using this setup, detailed quantitative comparisons between measurements and theoretical predictions can be carried out, focusing on many relevant topics in the undergraduate physics curriculum, such as the ‘radius of gyration’, conservation of energy, moment of inertia, constraint and reaction forces, and the behaviour of the centre of mass. (Some figures may appear in colour only in the online journal)

Using the idea of correlation to understand liquid behaviour

The use of probabilistic concepts is suggested as a way to explore the main differences in the behaviours of solids, liquids and gases with high school pupils. The idea of correlation is introduced with reference to macroscopic systems and then applied to describe the link between particles in solids, liquids and gases: analysis of the graphs of the radial distribution function allows pupils to construct a representation of how the three states of matter are differentiated by the nature of their order and to explain phenomenological observations. Results of a first trial of the proposal with pupils attending the final year of high school are presented.

Improving the connection between the microscopic and macroscopic approaches to thermodynamics in high school

In this article we discuss a teaching learning sequence on basic thermodynamics, spanning the first and second principle, and the concepts of irreversibility and entropy, intended for use in secondary school. With respect to previous works we emphasise the importance of discussing the compatibility between the time reversal symmetry of Newtons laws and the irreversibility embodied in the second principle of thermodynamics in order to completely exploit the possibility of connecting the microscopic and macroscopic perspectives. The sequence was tested in an Italian secondary school, and the results obtained from a questionnaire which combines several test items used in previous studies at university level are consistently comparable with or better than those reported for undergraduate students on the same questions over a range of topics. Thus, our work suggests that the microscopic approach is a viable option for the teaching of thermodynamics at the secondary school level; and the understanding of macroscopic concepts is not impaired, but possibly enhanced, by the adoption of such a teaching strategy.