• Journal of Educational Research in Mathematics
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• v.16 no.1
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• pp.25-41
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• 2006

The purpose of this study was to analyze teachers' pedagogical content knowledge (PCK) about area of plane figure and how it was actualized in instruction. As an exploratory, qualitative, and comparative case study, 2 fifth-grade teachers were selected. Semi-structured interviews with the leachers were conducted in order to explore their PCK with regard to the area of plane figure. A total of 14 mathematics instructions were videotaped and transcribed. Teachers' PCK and classroom teaching practices were analyzed in detail into 3 categories: (a) knowledge of mathematics contents, (b) knowledge of students' understanding, and (c) knowledge of instructional methods. As such, this paper provided a detailed description on each teacher's PCK and her teaching practice. The results showed that teachers' PCK had a significant impact on instruction. The teacher who had rich knowledge about the area of plane figure was able to encourage students to understand the concept of area and to or explore the principles behind formula calculating various areas of plane geometry. The results demonstrated the importance of individual components of PCK as well as that of overall level of PCK. Different aspects of teaching practices were observed as to how the teachers had internalized PCK. On the basis of a close relationship between teachers' PCK and their teaching practice, this paper finally raised several implications for teachers' professional development for effective mathematics instruction.