Forum on Education of The American Physical Society
Summer 2005 Newsletter



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Physics by Inquiry: A research-based approach to preparing K-12 teachers of physics and physical science

Lillian C. McDermott, Paula R.L. Heron and Peter S. Shaffer, Department of Physics, University of Washington, Seattle, WA

The Physics Education Group at the University of Washington (UW) has been conducting special courses for K-12 teachers for more than 30 years. We have developed a sequence of academic-year courses for prospective elementary and middle school teachers and another sequence for prospective high school teachers.[i] We also conduct an intensive NSF-funded six-week Summer Institute for Inservice Teachers that has similar goals. The materials used in both our preservice and inservice courses are drawn from Physics by Inquiry (PbI), a self-contained, laboratory-based curriculum that we have developed for use in university courses to prepare K-12 teachers to teach physics and physical science.[ii] The emphasis in this paper is on elementary and middle school. However, most of the discussion is applicable to the preparation of high school teachers.

I. Illustration of research-based instructional approach

We have selected electric circuits as a context in which to illustrate the instructional approach that has guided our development of PbI and our special courses for teachers. This topic is included in all K-12 standards-based science curricula. In particular, activities based on batteries and bulbs are common in elementary school. The equipment is inexpensive. There is a solid research base and a documented record of effectiveness.[iii] An additional motivation for this choice of topic is the availability of several published articles that should be helpful to faculty who may want to use the curriculum.3

A. Investigation of conceptual understanding

Research by our group on student understanding of electric circuits has extended over a period of many years. Since the results are well known by now, only a brief discussion of one question is presented here. In Fig. 1 are three circuits containing identical bulbs and identical ideal batteries. The question asks for a ranking by brightness of the five bulbs and an explanation of reasoning. The correct response is A=D=E>B=C.

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Figure 1: The five bulbs are identical and the batteries are identical and ideal. Rank the five bulbs from brightest to dimmest. Explain your reasoning.

This question was administered to more than 1000 students in introductory calculus-based physics. Before or after standard instruction in lecture and laboratory, student performance was essentially the same. Only about 15% of the students have responded correctly. The same question produced similar results when administered to high school physics teachers and to university faculty in other sciences and mathematics, all of whom had studied introductory physics. Analysis of the responses enabled us to identify specific difficulties. Two common mistaken beliefs were that the battery is a constant current source and that current is "used up" in a circuit. Most responses indicated lack of a conceptual model for a simple circuit. Reliance on rote use of inappropriate formulas was common. When the same question was posed to graduate students in the UW Physics Ph.D. program (many of whom are TA's in introductory physics), about 70% answered correctly. These findings motivated the development of the Electric Circuits module in PbI and the corresponding tutorial in Tutorials in Introductory Physics.[iv]

B. Instruction by guided inquiry

To prepare teachers to teach the topic of electric circuits by inquiry, we engage them in the step-by-step process of constructing a qualitative model that they can use to predict and explain the behavior of circuits consisting of batteries and bulbs.[v] The students are guided through carefully sequenced activities and questions to make observations that they can use as the basis for their model. They begin by trying to light a small bulb with a battery and a single wire. They develop an operational definition for a complete circuit. Exploring the effect of adding more bulbs and wires to the circuit, they find that their observations are consistent with the assumptions that a current exists in a complete circuit and that the relative brightness of identical bulbs indicates the relative magnitude of the current. In other experiments - some suggested, some of their own devising - they find that the brightness of individual bulbs depends both on how many are in the circuit and on how they are connected to the battery and to one another. They construct the concept of electrical resistance and find that they can predict the behavior of many, but not all, circuits of identical bulbs. They recognize the need to extend their model beyond current and resistance to include the concept of voltage (later refined to potential difference).

As bulbs of different resistance and additional batteries are added, the students find that they need additional concepts to account for the behavior of more complicated circuits. They are guided in developing more complex concepts, such as electrical power and energy. Through deductive and inductive reasoning, the students construct a model that can account for relative brightness in any circuit consisting of batteries and bulbs. Throughout the entire process of model development, the curriculum addresses specific difficulties that have been identified through research.

Teachers need to synthesize what they have learned, to reflect on how their understanding has evolved, and to try to identify critical issues that need to be addressed for meaningful learning to occur. As they progress in their investigation of electric circuits, the students are given many opportunities to express their ideas in writing.

C. Assessment of effectiveness

Although many of the elementary teachers in our courses have had considerably less preparation in physics than students in the standard introductory courses, their performance on qualitative questions has been consistently better. The circuit in Fig. 2 provides a good example of what teachers without a strong mathematical background, but with good conceptual understanding, can do. The students are asked to rank the bulbs according to brightness. Reasoning on the basis of a model based on the concepts of current and resistance, almost all elementary teachers who have taken our courses predict correctly that E>A=B>C=D. This question is beyond the capability of most college and university students who have had standard instruction in introductory physics.

circuit.jpg (6004 bytes)

Figure 2: The five bulbs are identical and the battery is ideal. Rank the five bulbs from brightest to dimmest. Explain your reasoning.

Other evidence for the effectiveness of this approach comes from the University of Cyprus, where the performance of two groups of prospective elementary school teachers was compared. (Fig. 3.) Both groups were taught by instructors who understood the material well and who taught in a manner consistent with constructivist pedagogy (i.e., the students were engaged in constructing their own understanding). One of the groups had studied electric circuits in PbI. [vi] This group consisted of two classes: one had just completed study of the material; the other class had done so the previous year. The second group had just completed the topic. They had been given "hands-on" experience with batteries and bulbs but the instruction they had received had not been guided by findings from research. Specific difficulties had not been explicitly addressed nor had the same emphasis been placed on the development of a coherent conceptual model.

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Figure 3: Student performance on free response and on multiple-choice questions on a post-instruction survey on electric circuits. The survey was administered to preservice elementary school teachers at the University of Cyprus. Two main groups of students were included in the survey: those who had used Physics by Inquiry (PbI) and those who had not. Some of the students had studied PbI one year before taking the test (Past PbI). All the others (Present PbI and Other) had just completed their study of this topic.

Both groups were given two types of post-tests: one consisted of free-response questions that asked for explanations of reasoning; the other contained multiple-choice questions taken from a multiple-choice test that has since been published.[vii] Both classes of students who had studied the material in Physics by Inquiry had mean scores greater than 80% on both tests. In the other group, mean scores were slightly above 40% on the multiple-choice test and less than 20% on the free-response test.[viii] Courses in which educational methodology is emphasized without sufficient emphasis on concept development seem to be no more effective than standard physics instruction.

II. Courses in physics and physical science for teachers

Results from research convinced us of the need to offer special physics courses for teachers. In all of these courses, all instruction takes place in the laboratory. There is no lecturing and only simple equipment is used.

The course for elementary school teachers does not proceed through the traditional physics sequence (kinematics, dynamics, electricity and magnetism, waves and optics). Instead, the topics have been selected to provide a firm foundation for teaching elementary school physical science. The module Electric Circuits discussed above is one example. In Properties of Matter, which probably is the best module with which to begin a course for elementary school teachers, students begin by constructing operational definitions for mass, volume, and density. They apply these concepts in predicting and explaining outcomes in situations of gradually increasing complexity, culminating with sinking and floating. PbI also includes modules on heat and temperature, magnetism, light and color, the sun and moon, and other phenomena encountered in daily life.

In the course for high school teachers, the students revisit many of the main topics in the introductory physics course (which is a prerequisite). These include kinematics, dynamics, waves, optics, electric circuits, and a few topics from modern physics. Graduate students in physics, mathematics, and other sciences often participate in this course, either as enrolled students or TA's. The course has provided a very positive environment for the preparation of future faculty to work productively with K-12 teachers.

In all of the modules in Physics by Inquiry, there is a strong emphasis on the development of important scientific skills, such as distinguishing between observations and inferences, controlling variables, proportional reasoning, deductive and inductive reasoning, etc. PbI fosters the simultaneous development of physical concepts, reasoning ability, and representational skills within a coherent body of content. The teachers go through the reasoning in depth and are guided in synthesizing what they have learned into a coherent conceptual framework. Since effective use of a particular instructional strategy is often content-specific, instructional methods are taught by example. If teaching methods are not studied in the context in which they are to be implemented, teachers may be unable to identify the elements that are critical. Thus they may not be able to adapt an instructional strategy that has been presented in general terms to specific subject matter or to new situations.

In addition to the courses described above, we offer a weekly Continuation Course that is open to all teachers within commuting distance of the UW who have participated in any of our preservice and inservice courses. The Continuation Course provides an opportunity for teachers to learn more physics and to consult on how best to apply what they have learned to K-12 classrooms. More importantly, the teachers develop a sense of community and mutual support. Teaching K-12 physics and physical science is often a professionally isolated activity. The Continuation Course has proved to be a major contributor to the long-term sustainability of our teacher preparation program.

III. Conclusion

The instructional approach, which has been illustrated in the context of electric circuits, has proved effective with teachers at all levels from elementary through high school. The process of hypothesizing, testing, extending, and refining a conceptual model to the point that it can be used to predict and explain a range of phenomena is the heart of the scientific method. It is a process that must be experienced to be understood.

We have been able to show that the demands in our courses for teachers match, or exceed, those of other physics courses at comparable levels. We have found that the sense of empowerment that results when teachers have developed a sound conceptual understanding of the science content that they are expected to teach greatly increases their confidence in their ability to deal with unexpected situations in the classroom.


This paper draws on the cumulative experience of past and present members of the Physics Education Group. Lezlie S. DeWater, and Donna Messina, K-12 teachers with our group, have made major contributions. We appreciate the support provided by the University of Washington Physics Department and the National Science Foundation.


[i] See L.C. McDermott, "Combined physics course for future elementary and secondary school teachers," Am. J. Phys. 42, 668-676 (1974) and L.C. McDermott, "Improving high school physics teacher preparation," Phys. Teach. 13, 523-529 (1975).

[ii] L. C. McDermott and the Physics Education Group at the University of Washington, Physics by Inquiry, Vols. I and II, (John Wiley & Sons Inc., New York NY, 1996).

[iii] L.C. McDermott and P.S. Shaffer, "Research as a guide for curriculum development: An example from introductory electricity. Part I: Investigation of student understanding," Am. J. Phys. 60, 994-1003 (1992); Printer's Erratum to Part I, ibid. 61, 81 (1993); and P.S. Shaffer and L.C. McDermott, "Research as a guide for curriculum development: an example from introductory electricity, Part II: Design of instructional strategies," ibid. 60, 1003-1013 (1992); L.C. McDermott, P.S. Shaffer, and C.P. Constantinou, "Preparing teachers to teach physics and physical science by inquiry," Phys. Educ. 35 (6) 411-416 (2000).

[iv] L.C. McDermott, P.S. Shaffer, and the Physics Education Group at the University of Washington, Tutorials in Introductory Physics, (Prentice Hall, Upper Saddle River NJ, 2002).

[v] The instructional sequence can be found in the Electric Circuits module in Volume II of Physics by Inquiry. (See Ref. 2.)

[vi] A Greek edition of Physics by Inquiry was used.

[vii] P.V. Engelhardt and R.J. Beichner, "Students' understanding of direct current resistive electrical circuits," Am. J. Phys. 72, 98-115 (2004).

[viii] This study is discussed in greater detail in the last article in Ref. 3.

Lillian C. McDermott, Peter S. Shaffer, and Paula R.L. Heron are faculty members in the Physics Education Group in the Physics Department at the University of Washington. The group consists of physics graduate students, postdocs, faculty and K-12 teachers who conduct a coordinated program of research, curriculum development, and instruction to improve student learning in physics (K-20). The group is engaged in ongoing research on the learning and teaching of physics that has resulted in more than 50 research articles. For more than 30 years, they have been deeply involved in the preparation of prospective and practicing teachers to teach physics and physical science by inquiry. The group has also published research-based tutorials to improve the effectiveness of instruction in introductory university physics.



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