missing; the concept of charge is not related to the concept of
current; and the directions of the arrows relating to the con-
cepts do not reflect a coherent understanding. These results
are consistent with previous research findings.^36
An analysis of the teachers’ discussions during this ses-
sion confirmed that the causal relationship between the elec-
tric field and current was deficient. They were frustrated to
find out that in spite of their experience, they still lacked
basic knowledge of physics.
The following are excerpts from these discussions:
iAlthough the topic of currents seems to be very
simple, the truth of the matter is that I have an uneasy feeling
when I teach it.
iiWell, sometimes I smooth things over.
iiiThe whole issue of an electromotive forceEMF
source is like a black box for me. What does the battery do?
I suspect that even chemistry teachers cannot provide an an-
swer.
ivI suggest asking Zvian expert physics teacherto
come to the next meeting.
In the course-leader journal, written after this session, it
was noted that the teachers had a hard time with the physics
of this topic and they asked for extra time to learn more
physics.
Step 2: Review of the literature. Teachers review the lit-
erature on physics as well as physics learning relevant to
their topic, and report on the main learning difficulties and
instructional strategies. The process is guided by the course
leaders, but teachers are asked to expand the suggested list of
references.
Results. The teachers were referred to the literature con-
cerning the physics of surface charge distribution that causes
the charges to flow, and to papers about innovative instruc-
tional strategies in this topic.^38 TableI presents the original
list of the teachers’ review of the literature as presented in
conference I.
After discussing the review of the literature, one of the
teachers said:
“You know what? The physics here is really complicated;
it is nice to find out that people tackle the same problems
everywhere.”
Step 3: Diagnosis. Teachers design, administer, and ana-
lyze a diagnostic questionnaire consisting of a few “simple”
questions to examine students’ understanding.
Results. Teachers usually compose examinations quite
easily. However, the requirement to compose a diagnostic
tool aimed at well-predefined goals was a new experience for
many of them. Besides the enrichment of their subject matter
knowledge and their pedagogical content knowledge, this
stage of the workshop enriched their general pedagogical
knowledge as well. Teachers raised questions and dwelled on
issues unfamiliar to them such as: “What is a diagnostic
tool? Does it have to be a questionnaire? What do we want to
find out about students’ understanding? What do we mean by
understanding?” According to the course-leader journal, fol-
lowing the development of the diagnostic tool, the teachers
suggested changing the plan of the course and asked for ad-
ditional lectures supplying information about the ideas of
“diagnosis” and “understanding.”
The group designed questions focusing on the relationship
between the electric field and current at different points of a
dc circuit at different times. Since the electric field between
the plates of a capacitor is studied in electrostatics and the
charging of a capacitor is studied in dc circuits, the teachers
decided to focus the questionnaire on the charging of a ca-
pacitor. TableIIpresents the list of goals for the diagnostic
questionnaire.TABLE I. Teachers’ present their review of the literature.aIssues regarding the physics raised by the review- How does the current “know” how to split in a junction?
- If the electric field exerts force on the charges, why is the drift velocity constant?
- How do the charges know how to move in a meandering wire?
bSelected insights regarding the teaching and learning of physics from the review- How do students explain current flow in an open circuit and what can be done about it?
- There is a gap between students’ conceptions of electric fields in the contexts of electrostatics and
electric circuits: electric field in electrostatics is usually conceived by students as a force that causes
charges to move, whereas in circuits, the electric field is conceived as a theoretical concept derived from
the concept of the potential difference. Introducing the changes in the distribution of surface charges in
electric circuits can help in bridging the gap. - The analysis of dc circuits is usually based on energy considerations without referring to the
microscopic aspects inside and outside the circuit.
cSelected instructional strategies from the review- Murzin, for example, describes Drude’s model as an explanation of charge flow in a circuit and the
relationship betweenjandE. - Parker and Chabay & Sherwood use the surface charge distribution to explain the electric field inside
and outside a current-carrying conductor. - Jefimenko suggests interesting experiments demonstrating electric fields inside and outside meandering
wires.
RESEARCH-DESIGN MODEL FOR PROFESSIONAL¼ PHYS. REV. ST PHYS. EDUC. RES. 2 , 020106 2006
020106-5