Research Matters - to the Science Teacher
No. 9702 Jan. 14,
Pedagogical Content Knowledge: Teachers' Integration of Subject
Matter, Pedagogy, Students, and Learning Environments
by Kathryn F. Cochran, University of Northern Colorado
"Those who can, do. Those who understand, teach."
(Shulman, 1986, p. 14)
Recently, there has been a renewed recognition of the importance
of teachers' science subject matter knowledge, both as a function of
research evidence (e.g., Ball & McDiarmid, 1990; Carlsen, 1987;
Hashweh, 1987), and as a function of literature from reform
initiatives such as the Holmes Group (1986) and the Renaissance Group
(1989). Not surprisingly, it has become clear that both
teachers' pedagogical knowledge and teachers' subject matter
knowledge are crucial to good science teaching and student
understanding (Buchmann, 1982, 1983; Tobin & Garnett, 1988).
The recent development of the National Science Education Standards
(NRC, 1996) and the Benchmarks for Science Literacy (AAAS, 1993) as
well as a multitude of state, district, and school level content area
standards, have further renewed emphasis on the importance of subject
matter. Moreover, these documents contain not only key subject matter
concepts for student learning, but they also inform pedagogical
issues related to science subject matter content.
The Nature of Pedagogical Content
In addition to teachers' subject matter (content) knowledge and
their general knowledge of instructional methods (pedagogical
knowledge), pedagogical content knowledge was originally
suggested as a third major component of teaching expertise, by Lee
Shulman (1986; 1987) and his colleagues and students (e.g. Carlsen,
1987; Grossman, Wilson, & Shulman, 1989; Gudmundsdottir, 1987a,
1987b; Gudmundsdottir & Shulman, 1987; Marks, 1990). This idea
represents a new, broader perspective in our understanding of
teaching and learning, and a special issue of the Journal of
Teacher Education (Ashton, 1990) was devoted to this topic.
Pedagogical content knowledge is a type of knowledge that is
unique to teachers, and is based on the manner in which teachers
relate their pedagogical knowledge (what they know about teaching) to
their subject matter knowledge (what they know about what they
teach). It is the integration or the synthesis of teachers'
pedagogical knowledge and their subject matter knowledge that
comprises pedagogical content knowledge. According to Shulman (1986)
pedagogical content knowledge
. . . embodies the aspects of content most germane to
its teachability. Within the category of pedagogical content
knowledge I include, for the most regularly taught topics in one's
subject area, the most useful forms of representation of those
ideas, the most powerful analogies, illustrations, examples,
explanations, and demonstrations - in a word, the ways of
representing and formulating the subject that make it
comprehensible to others . . . [It] also includes an
understanding of what makes the learning of specific concepts easy
or difficult: the conceptions and preconceptions that students of
different ages and backgrounds bring with them to the learning
Pedagogical content knowledge is a form of knowledge that makes
science teachers teachers rather than scientists (Gudmundsdottir,
1987a, b). Teachers differ from scientists, not necessarily in the
quality or quantity of their subject matter knowledge, but in how
that knowledge is organized and used. In other words, an experienced
science teacher's knowledge of science is organized from a
teaching perspective and is used as a basis for helping
students to understand specific concepts. A scientist's knowledge, on
the other hand, is organized from a research perspective and
is used as a basis for developing new knowledge in the field. This
idea has been documented in Biology by Hauslein, Good, & Cummins
(1992), in a comparison of the organization of subject matter
knowledge among groups of experienced science teachers, experienced
research scientists, novice science teachers, subject area science
majors, and preservice science teachers. Hauslein et al. found that
science majors and preservice teachers both showed similar, loosely
organized subject matter knowledge; and that the subject matter
knowledge of the novice and experienced teachers and the research
scientists was much deeper and more complex. However, compared to the
researchers (who showed a flexible subject matter structure), the
teachers showed a more fixed structure, hypothesized to result from
Cochran, DeRuiter, & King (1993) revised Shulman's original
model to be more consistent with a constructivist perspective on
teaching and learning. They described a model of pedagogical content
knowledge that results from an integration of four major
components, two of which are subject matter knowledge and pedagogical
knowledge. The other two other components of teacher knowledge also
differentiate teachers from subject matter experts. One component is
teachers' knowledge of students' abilities and learning strategies,
ages and developmental levels, attitudes, motivations, and prior
knowledge of the concepts to be taught. Students' prior knowledge has
been especially visible in the last decade due to literally hundreds
of studies on student misconceptions in science and mathematics. The
other component of teacher knowledge that contributes to pedagogical
content knowledge is teachers' understanding of the social,
political, cultural and physical environments in which students are
asked to learn. The model in Figure 1 shows that these four
components of teachers' knowledge all contribute to the integrated
understanding that we call pedagogical content knowledge; and the
arrows indicate that pedagogical content knowledge continues to grow
with teaching experience. The integrated nature of pedagogical
content knowledge is also described by Kennedy (1990).
Figure 1. Pedagogical Content Knowledge in the Experienced
Hashweh (1985, 1987) conducted an extensive study of three physics
teachers' and three biology teachers' knowledge of science and the
impact of that knowledge on their teaching. All six teachers were
asked about their subject matter knowledge in both biology and
physics, and they were asked to evaluate a textbook chapter and to
plan an instructional unit on the basis of that material. Given a
concept like photosynthesis for example, the biology teachers knew
those specific misconceptions that students were likely to bring to
the classroom (such as the idea that plants get their food from the
soil) or which chemistry concepts the students would need to review
before learning photosynthesis. The biology teachers also understood
which ideas were likely to be most difficult (e.g. how ATP-ADP
transformations occur) and how best to deal with those difficult
concepts using a variety of analogies, examples, demonstrations and
models. The biology teachers could describe multiple instructional
"tools" for these situations; but, although they were experienced
teachers, they had only very general ideas about how to teach
difficult physics concepts. The physics teachers, on the other hand,
could list many methods and ideas for teaching difficult physics
concepts, but had few specific ideas for teaching difficult biology
When the teachers in Hashweh's study were asked about their
subject matter knowledge in the field that was not their specific
field, they showed more misconceptions, more misunderstandings, and a
less organized understanding of the information. Within their own
fields, they were more sensitive to subtle themes presented in
textbooks, and could and did modify the text material based on their
teaching experiences. Moreover, they were more likely to discover and
act on student misconceptions. The teachers used about the same
number of examples and analogies when planning instruction in both
fields, but those analogies and examples were more accurate and more
relevant in the teachers' field of expertise.
Other studies have shown that new teachers have incomplete or
superficial levels of pedagogical content knowledge (Carpenter,
Fennema, Petersen, & Carey, 1988; Feiman-Nemser & Parker,
1990; Gudmundsdottir & Shulman, 1987; Shulman, 1987). A novice
teacher tends to rely on unmodified subject matter knowledge (most
often directly extracted from the curriculum) and may not have a
coherent framework or perspective from which to present the
information. The novice also tends to make broad pedagogical
decisions without assessing students' prior knowledge, ability
levels, or learning strategies (Carpenter, et al., 1988). In
addition, preservice teachers have been shown to find it difficult to
articulate the relationships between pedagogical ideas and subject
matter concepts (Gess-Newsome & Lederman, 1993); and low levels
of pedagogical content knowledge have been found to be related to
frequent use of factual and simple recall questions (Carlsen, 1987).
These studies also indicate that new teachers have major concerns
about pedagogical content knowledge, and they struggle with how to
transform and represent the concepts and ideas in ways that make
sense to the specific students they are teaching (Wilson, Shulman,
& Richert, 1987). Grossman (1985, cited in Shulman, 1987) shows
that this concern is present even in new teachers who possess the
substantial subject matter knowledge gained through a master's degree
in a specific subject matter area, and Wilson (1992) documents that
more experienced teachers have a better "overarching" view of the
content field and on which to base teaching decisions.
These and other studies show that pedagogical content knowledge is
highly specific to the concepts being taught, is much more than just
subject matter knowledge alone, and develops over time as a result of
teaching experience. What is unique about the teaching process is
that it requires teachers to "transform" their subject matter
knowledge for the purpose of teaching (Shulman, 1986). This
transformation occurs as the teacher critically reflects on
and interprets the subject matter; finds multiple ways to
represent the information as analogies, metaphors, examples,
problems, demonstrations, and/or classroom activities; adapts the
material to students' developmental levels and abilities, gender,
prior knowledge, and misconceptions; and finally tailors the
material to those specific individual or groups of students to whom
the information will be taught. Gudmundsdottir (1987a, b) describes
this transformation process as a continual restructuring of subject
matter knowledge for the purpose of teaching; and Buchmann (1984)
discusses the importance of science teachers maintaining a fluid
control or "flexible understanding" (p. 21) of their subject
knowledge, i.e. be able to see a specific set of concepts from a
variety of viewpoints and at a variety of levels, depending on the
needs and abilities of the students.
Recommendations for Teachers
Where Should We Go From Here?
- The first recommendation that can be made for teachers is for
them to begin to more often reflect on or think about why
they teach specific ideas the way they do. Teachers know much more
about teaching subject matter concepts to students than they are
aware. This is pedagogical content knowledge; and many teachers
don't think about this knowledge as important. It is important,
though, because it determines what a teacher does from minute to
minute in the classroom, as well as influencing long term
To become more aware of this knowledge and to be able to more
clearly think about it, teachers can find ways to keep track of
this information, just as they ask students to do with the data
collected in lab assignments. One way is to keep a personal
notebook describing their teaching, even just once a week or so
for a few difficult concepts. Another strategy is to videotape or
audiotape a few class periods just to help see what's happening in
the classroom. (It's not necessary to have anyone but the teacher
see or listen to the tape.) Then teachers can start to think about
the following types of questions. Which ideas need the most
explanation? Why are those ideas more difficult for the students?
What examples, demonstrations, and analogies seemed to work the
best? Why did they work or not work? Which students did
they work best for?
- Teachers can try new ways of exploring how the students are
thinking about the concepts being taught. Ask students about how
and what they understand (not in the sense of a test, but in the
sense of an interview). Ask students what "real life" personal
situations they think science relates to. Try to get inside their
heads and see the ideas from their point of view.
- Start discussions with other teachers about teaching. Take the
time to find someone you can share ideas with and take the time to
learn to trust each other. Exchange strategies for teaching
difficult concepts or dealing with specific types of students. Get
involved in a peer coaching project in your school or district.
District faculty development staff or people at a local university
can help you get one started and may be able to provide substitute
support. Ask about telephone hot-lines and computer networks for
teachers, and explore the world wide web.
- Get involved in action research projects. Much of the newestM and most important research is being conducted by teachers. Take a
class at your nearest university and find out what is going on.
Get involved with a mentor teacher program or a teacher on special
assignment program. Join organizations and go to conferences such
as the national or regional National Science Teachers Association
or the NARST
meetings. There are also often summer workshops and institutes in
specific fields in science at many universities and colleges.
Contemporary research has focused on how to describe teachers'
pedagogical content knowledge and how it influences the teaching
process. We have yet, however, to fully understand the four
components of this model, and we have yet to clearly understand how
they really develop. We also know very little about how to enhance
pedagogical content knowledge in preservice and inservice programs.
Teacher involvement in research and university preparation programs
is crucial for the development of this important idea and its
usefulness for the improvement of science teaching.
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Research Matters - to the Science
is a publication of NARST