Abstract:
Research has shown that a high level of content knowledge (CK) is
necessary but not sufficient to develop the special knowledge base
of expert teachers known as pedagogical content knowledge (PCK).
This study contributes towards research to quantify the relationship
between CK and PCK in science. In order to determine the
proportion of the variance in PCK accounted for by the variance in
CK, instruments are required which are valid and reliable as well
as being unidimensional to measure person abilities for CK and
PCK. An instrument consisting of two paper-and-pencil tests was
designed to assess Grade 12 teachers CK and PCK in organic
chemistry. We used the Rasch measurement model to convert raw
score data into interval measures and to provide empirical
evidence for the validity, reliability and unidimensionality of the
tests. The correlation between CK and PCK was estimated as r =
.66 (p < .001). We found evidence to suggest that while topicspecific
PCK (TSPCK) develops with increasing teaching experience,
high levels of CK can be acquired with limited teaching
experience. These findings support the hypothesis that CK is a
requirement for the development of TSPCK; proficiency in CK is,
however, not necessarily associated with high levels of TSPCK.
