ICPE Logo International Newsletter on Physics Education

International Commission on Physics Education

International Union of Pure and Applied Physics

Number 32, April 1996

Table of Contents

Qualitative vs. Quantitative Thinking:
Are We Teaching the Right Thing?

Eric Mazur, Harvard University, USA

For the past eight years, I have been teaching an introductory physics course for engineering and science concentrators at Harvard University. Teaching this class, which does not include any physics majors, is a challenging experience because the students take this course as a concentration requirement, not because of a genuine interest in physics. At the same time, it can be a very rewarding experience when, at the end of the semester, students show much more appreciation for the subject matter.

I used to teach a fairly traditional course in an equally traditional lecture-type presentation, enlivened by classroom demonstrations. I was generally satisfied with my teaching during these years--my students did well on what I considered pretty difficult problems and the feedback I received from them was positive.

But about a year ago, I came across a series of articles by David Hestenes of Arizona State University(1) that completely and permanently changed my views on teaching. In these articles, Hestenes shows that students enter their first physics course possessing strong beliefs and intuitions about common physical phenomena. These notions are derived from personal experiences and color students' interpretations of material presented in the introductory course. Instruction does very little to change these "common-sense" beliefs.

For example, after a couple of months of physics instruction, all students will be able to recite Newton's third law--"action is reaction" and most of them can apply this law in problems. But a little probing beneath the surface quickly shows that the students lack any fundamental understanding of this law. Hestenes provides many examples in which the students are asked to compare the forces of different objects on one another. When asked, for instance, to compare the forces in a collision between a heavy truck and a light car, a large fraction of the class firmly believes the heavy truck exerts a larger force on the light car than vice versa. My first reaction was "Not my students!" I was intrigued, however. To test my own students' conceptual understanding I developed a computer program based on the tests developed by Hestenes.

The first warning came when I gave the test to my class and a student asked, "Professor Mazur, how should I answer these questions? According to what you taught us, or by the way I think about these things?" While baffled, I did not get the message quite yet. The results of the test, however, were undeniably eye-opening: the students fared hardly better on the Hestenes test than on their mid-term examination on rotational dynamics. Yet, I think the Hestenes test is simple; yes, probably too simple to be considered seriously for a test by many of my colleagues-- while material covered by the examination (rotational dynamics, moments of inertia) was, in my opinion, of far greater difficulty.

I spent many, many hours discussing the results of this test with my students one-on-one. The old feeling of satisfaction turned more and more into a feeling of sadness and frustration. How could these undoubtedly bright students, capable of solving complicated problems, fail on these ostensibly "simple" questions?

On the following examinations, I paired "simple," qualitative questions with more "difficult," quantitative problems on the same physical concept. Much to my surprise, some 40% of the students did better on the quantitative problems than on the conceptual ones. Slowly, the underlying problem revealed itself: many students concentrate on learning "recipes," or "problem solving strategies" as they are called in textbooks, without bothering to be attentive to the underlying concepts. Many pieces of the puzzle suddenly fell into place. The continuing requests by students to do more and more problems and less and less lecturing -- doesn't the traditional lecture overemphasize problem-solving over conceptual understanding? The unexplained blunders I had seen from apparently "bright" students -- problem-solving strategies work on some, but surely not all problems. Students' frustration(2) with physics -- how boring must physics be when it is reduced to a set of mechanical recipes without any apparent logic. And yes, Newton's third law is second nature to me -- it's obviously right, but how do I convince my students? Certainly not by just reciting the law and then blindly using it in problems.

Just a year ago, I was entirely oblivious to this problem. I now wonder how I could be fooled into thinking I did a credible job teaching introductory physics. While several leading physicists have written on this problem(3), I believe many teachers, like myself just a year ago, are still unaware of it. A first step in remedying this situation is to expose the problem in one's own class. The key, I believe, is to ask simple questions that focus on single concepts. The result is guaranteed to be an eye-opener even for seasoned teachers.


  1. Ibrahim Abou Halloun and David Hestenes, Am J. Phys. 53 (1985), 1043-1055; 53 (1985), 1056-1065; 55 (1987), 455-462; David Hestenes, Am. J. Phys., 55 (1987), 440-454.

  2. Sheila Tobias, They're Not Dumb, They're Different, Research Corp., Tucson Ariz. 1990.

  3. See for example Arnold Arons, A Guide to Introductory Physics Teaching,John Wiley & Sons, New York. NY, 1990; Richard P. Feynman, The Feynman Lectures, Vol.. 1. Addison-Wesley, New York NY, (1989), p. 1-1; Kenneth Wilson, Phys. Today, 44:9 (1991), 71-73.

ERIC MAZUR is Gordon McKay Professor of Applied Physics and Professor of Physics at Harvard University. He divides his time between research in laser physics and teaching.

(c) PHOTONICS NEWS February 1992
reprinted with permission

Other relevant references:

  1. David Hestenes, Malcolm Wells, & Gregg Swackhammer, "The Force Concept Inventory," The Physics Teacher 30, (Mar 1992), 141-158.

  2. David Hestenes and Malcolm Wells, "A Mechanics Baseline Test," The Physics Teacher 30, (Mar 1992), 159-166.


Guest Editorial:

The Change in Science Education, or "It's Pretty Scary"

Paul Black, King's College, London, UK

I have just completed work on an international project studying change in science mathematics and technology education through case studies of twenty-three innovations in thirteen countries.* Two of the many different issues raised in these studies stand out particularly-- the future of science curriculum and the professional role of teachers in charge.

To take the future of science curriculum first, it is notable that in many countries, for example, Japan, Australia, Germany and Spain, a change in the nature and aims of school science education is taking place which, while it is not novel, will have far reaching consequences. It is a move towards the practical and the everyday as the contexts in which to learn science. The traditional route -- to teach deep concepts and then show how they lead to applications -- is being inverted. The applications now come first, so the work is based on topics which are chosen for their interest and relevance to young people-- to their daily lives and to their future as citizens. Typical examples are pollution, conservation, global warming, and genetic engineering. The task of curriculum design is then more complex. What has to be achieved is to articulate the way such topics are pursued, so that the studies will lead to acquisition of the profound concepts and stringent methodologies of science. Students need these both to penetrate further into the issues than the TV sound-bites allow, and to acquire an authentic and useful basis for their future interest in science.

However, this movement has two important consequences for those committed to physics education. One is that the changes are accompanied by a move away from the teaching of the separate sciences in secondary schools, towards having a single course in which these are taught in a coordinated and integrated way. How is physics education to move forward in such a scenario? I personally do not believe in so-called "integrated" science, because I think that there are important and deep differences between the philosophies and methodologies used (say) by those studying fundamental particle interactions and those studying the social life of chimpanzees. But I strongly believe in coordination: for example-- in how many countries do young students learn about energy concepts in three different ways from a physics teacher, a chemistry teacher and a biology teacher, when those three teachers do not work closely together to prepare a single coherent sequence of learning for students? More generally, how far should we now go in studying and conferencing about physics education without involving our colleagues in the neighboring sciences?

The other important consequence is about authority and ownership. The shift described above is bound to worry those in higher education, because it will mean that the preparation of their students will be, at least, very different. But there is a broader implication. In the past it is the academics in (say) physics who have had the right to decide the curriculum for school physics. In some countries, academics consult school teachers in such work. In other countries now, our innovations show that teachers are taking over-- so that they are deciding what their students need. who should decide? Do politicians, or citizen groups concerned about the uses and misuses of science, or those in business and industry where the majority of scientists actually work, have a right to share in curriculum decisions? And if so, how are such rights to be exercised? And if such voices did have power, what might happen to physics education?

This last point connects with my second main issue-- how the average teacher copes with change. The question raised above is whether teachers have the right to wrest control over new aims for science teaching from the academics. However, whether new ideas are formulated by academics or by leading teachers of by other alliances, all such ideas face the problem of achieving effective implementation in all classrooms in a country or state. Where the ideas require a work on new topics, or a capacity to think about familiar topics in a quite new way, those with weak qualifications might not even try. Even with teachers who are very well qualified, it takes substantial time and effort to change one's practice. The reason is obvious-- success, or even survival, in the complex world of the classroom is hard to achieve, and to change one's work in any important aspect is to put that hard-won success at risk. As a teacher in one of the case studies put it, "it's pretty scary."

All of this would be true even if those planning a change knew exactly how it would best work across the majority of classrooms. Usually they do not-- it is only through an iteration between the harsh constraints of daily practice and reformulation of the ideals that a workable implementation can be fashioned. And the prospect is even more daunting-- classrooms differ across any region, and teachers' own styles differ, so that a personal adaptation has to be forged by every teacher for herself or himself.

Thus a reform cannot work by a hasty top-down imposition. It has to be achieved slowly through the gradual involvement of teachers who are given time, support, and flexibility to make the reform ideas their own. Almost all of the reforms of the past thirty years failed because they did not take these requirements seriously. In many cases they tried to move teachers too far and too fast from their present practices and expertise. So perhaps we ought to approach change rather differently-- by starting from consideration of the present strengths of those teaching physics and fashioning modest changes which can best build upon these.

* Changing the Subject: Innovation and Change in Science, Mathematics and Technology Education. Edited by P.J. Black and M.A. Atkin. New York and London: Routledge for OECD (Organisation for Economic Cooperation and Development) ISBM 0415 146 232.

Dr. Black is a professor at King's College, London and is chairman of the ICPE


In questions of science the authority of a thousand is not worth the humble reasoning of a single individual.

Galileo Galilei (1564-1642)

A man does not gain the status of Galileo merely because he is persecuted; he must also be right.

Stephen Jay Gould -- Ever Since Darwin 1977


EUPEN Partners Sought

As reported in Europhysics News 26 (19995) 69, the Scientific Committee of the Thematic Evaluation Conference - Physics Studies for Tomorrow's Europe (Ghent, 7-8 April 1995) created a European Physics Education Network (EUPEN). A Steering Committee was formed and it has prepared a proposal for a Thematic Network in the framework of the SOCRATES program of the European Union (EU). Organizations throughout Europe, including all university-level physics faculties/departments, have been invited to join the initiative by completing a preliminary partnership agreement. Each participating institution is free to chose the level of involvement and the (related) willingness to supply complementary funding.

Societies and associations concerned with physics education will be invited to join the network as Associate Members.

EUPEN Project Outline

The main initiatives envisioned are:


EUPEN will promote specific activities linked to these subjects, according to a predetermined schedule and a list of priorities. The actions needed to carry out the project will be organized by means of conferences and/or by a peer review.

Organizational details will be optimized once the level of involvement of each partner institution is known. The coordinator would be the University of Ghent, and a Steering Committee, grown out of the Scientific Committee of the Thematic Evaluation Conference on Physics will set up the necessary administrative structures (e.g., sub-networks specialized in one or more subjects of the project) as well as a convention for member institutions outlining quality and good practice.


The main outcome would be:

Reprinted from Europhysics News 27(1) 96. With permission.


Upcoming Conferences:


To know and not to act is not yet to know.

Wang Shou-Jen (1472-1528)

Contact with strange civilizations brings new standards of value, with which the native culture is re-examined and re-evaluated, and conscious reformation and regeneration are the natural outcome.

Hu Shih (1891-1962)



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