• Journal of Educational Research in Mathematics
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• v.25 no.3
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• pp.263-279
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• 2015

The introduction of real numbers is one of the most difficult steps in the teaching of school mathematics since the mathematical justification of the extension from rational to real numbers requires the completeness property. The author elucidated what questions about real numbers can be unanswered as the "institutional didactic void" in school mathematics defining real numbers as the union of the rational and irrational numbers. The pre-service teachers' explanations on the extension from rational to real numbers and the raison d'$\hat{e}$tre of arbitrary non-recurring decimals showed the superficial and fragmentary understanding of real numbers. Connecting school mathematics to university mathematics via the didactic void, the author discussed how pre-service teachers could break the illusion of transparency about the real number.

• Journal of Elementary Mathematics Education in Korea
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• v.19 no.4
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• pp.563-588
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• 2015

In elementary school, didactical transposition is inevitable due to several reasons. In mathematics, addition and multiplication are taught as binary operations, subtraction and division are taught as unary operations. But in elementary school, we try to teach all the four operations as binary operations by didactical transposition. In 'Mastering' the concepts of the four operations, the way of concept introduction is dealt importantantly. So it is different from understanding the four operations. In this study, we analyzed the four operations of natural numbers and fractions from two perspectives: concept understanding (how to introduce concepts and how to choose an operation) and connection between the operations. As a result, following implications were obtained. In division of fractions, students attempted a connection with multiplication of fractions right away without choosing an operation, based on the situation. Also, to understand division of fractions itself, integrate division of fractions presented from the second semester of the fifth grade to the first semester of the sixth grade are needed. In addition, this result can be useful in the future textbook development.

• Journal of Educational Research in Mathematics
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• v.24 no.3
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• pp.311-331
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• 2014

For preservice teachers' instrumental-to-relational pedagogical content knowledge transformations, this research designed several didactical tasks based on Kinach's cognitive strategies. The researcher identified preservice teachers' understanding about what is a definition and how to teach it. By challenging their fixed ideas about definitions, the researcher could motivate them to embrace the new teaching approach which guides reinvention of definitions. The PCK development was not the simple process of filling their tabular rasa PCK with theories of mathematics education, but the dialectical process of identifying, challenging, changing and extending preservice teachers' existent PCK. This research will contribute to explore new directions of mathematics teachers' PCK development and the method of teacher education.

• Education of Primary School Mathematics
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• v.11 no.2
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• pp.141-159
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• 2008

The purpose of this study id to delve into how elementary mathematics textbook deal with the quadrilaterals from a view of Didactic Transposition Theory. Concerning the instruction period and order, we have concluded the following: First, the instruction period and order of quadrilaterals were systemized when the system of Euclidian geometry was introduced, and have been modified a little bit since then, considering the psychological condition of students. Concerning the definition and presentation methods of quadrangles, we have concluded the following: First, starting from a mere introduction of shape, the definition have gradually formed academic system, as the requirements and systemicity were taken into consideration. Second, when presenting and introducing the definition, quadrilaterals were connected to real life. Concerning the contents and methods of instruction, we have concluded the following: First, the subject of learning has changed from textbook and teachers to students. Second, when presenting and introducing the definition, quadrilaterals were connected to real life. Third, when instructing the characteristics and inclusive relation, students could build up their knowledge by themselves, by questions and concrete operational activities. Fourth, constructions were aimed at understanding of the definition and characteristics of the figures, rather than at itself.

• Journal of Elementary Mathematics Education in Korea
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• v.9 no.2
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• pp.161-180
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• 2005

The purpose of this study is to delve into how elementary mathematics textbooks deal with the areas of triangles and quadrilaterals from a viewpoint of the Didactic Transposition Theory. The following conclusion was derived about the teaching of the area concept: The area concept started to be taught perfectly in the 7th curricular textbook, and the focus of area teaching was placed on the area concept, since learners were gradually given opportunities to compare and measure areas. As to the area formulae of triangles and quadrilaterals, the following conclusions were made: First, the 1st curricular, the 2nd curricular and the 3rd curricular textbooks placed emphasis on transposition by textbooks, and the 4th curricular, the 5th curricular and the 6th curricular textbooks accentuated transposition by teachers. The 7th curricular textbooks put stress on knowledge construction by learners; Second, the focus of teaching shifted from a measurement of area to inducing learners to make area formula. Namely, the utilization of area formula itself was accentuated, while algorithm was emphasized in the past; Third, the way to encourage learners to produce area formula changed according to the curricula and in light of learners' level, but a wide range of teaching devices related to the area formulae were removed, which resulted in offering less learning chances to students; Fourth, what to teach about the areas of triangles and quadrilaterals was gradually polished up, and the 7th curricular textbooks removed one of the overlapped area formula of triangle.

• School Mathematics
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• v.10 no.1
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• pp.43-61
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• 2008

This study is based on the pedagogical aspect that both connections of mathematical concepts and a geometric approach enhance the understanding of structures in school mathematics. This study is to investigate the graphical properties of quadratic functions such as symmetry, coordinates of vertex, intercepts and congruency through the geometric properties of graphs of linear functions. From this investigation this study would give suggestions on a new pedagogical perspective about current teaching and learning methods of quadratic function graphs which is focused on routine algebraic transformation of the completing squares. In addition, this study would provide the topic of quadratic function graphs with the understanding of geometric perspective.

• Journal of Educational Research in Mathematics
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• v.18 no.3
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• pp.353-372
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• 2008

This study looks around the goals of teaching statistical graphs that are introduced in the seventh Korean Curriculum for Elementary School and in the Principles and Standards for School Mathematics(NCTM, 2000), and these are compared. We compare how to transpose statistical graphs didactically between the Korean and MiC textbooks. For it, it examines the types of statistical graphs, the methods defining them, and the making connections and comparing among them, which are content components in the chapters on statistical graphs. The results show that in contrast to the Korean textbooks, NCTM(2000) has allowed students to develop their own expression for data, to compare results analysed within different graphs, and to consider a graph as a whole in the goals of teaching statistical graphs. MiC textbooks have introduced the number-line plot and the box plot more than Korean. Although both of Korean and MiC textbooks usually use extensive methods for defining individual graphs, the former use extensive methods together with synonymic methods and the latter use extensive methods with the characteristics of graphs. Also, the number-line plot is defined using operative method in the MiC textbooks. MiC textbooks contain various activities for connecting and comparing graphs, but there are comparatively few comparing activities in the Korean textbooks.

• Journal of Elementary Mathematics Education in Korea
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• v.7 no.1
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• pp.45-64
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• 2003

This study analyzes divisor and multiple in elementary school mathematics textbooks published according to the first to the 7th curriculum, in a view point of the didactic transposition theory. In the first and second textbooks, the divisor and the multiple are taught in the chapter whose subject is on the calculations of the fractions. In the third and fourth textbooks, divisor and multiple became an independent chapter but instructed with the concept of set theory. In the fifth, the sixth, and the seventh textbooks, not only divisor multiple was educated as an independent chapter but also began to be instructed without any conjunction with set theory or a fractions. Especially, in the seventh textbook, the understanding through activities of students itself are strongly emphasized. The analysis on the each curriculum periods shows that the divisor and the multiple and the reduction of a fractions to the lowest terms and to a common denominator are treated at the same period. Learning activity elements are increase steadily as the textbooks and the mathematical systems are revised. The following conclusion can be deduced based on the textbook analysis and discussion for each curriculum periods. First, loaming instruction method also developed systematically with time. Second, teaching method of the divisor and multiple has been sophisticated during the 1st to 7th curriculum textbooks. And the variation of the teaching sequences of the divisor and multiple is identified. Third, we must present concrete models in real life and construct textbooks for students to abstract the concepts by themselves. Fourth, it is necessary to develop some didactics for students' contextualization and personalization of the greatest common divisor and least common multiple. Fifth, the 7th curriculum textbooks emphasize inquiries in real life which teaming activities by the student himself or herself.

• School Mathematics
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• v.5 no.1
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• pp.115-133
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• 2003

Investigation of the students' mathematical misconceptions is very important for improvement in the school mathematics teach]ng and basis of curriculum. In this study, we categorize second-grade middle school students' misconceptions on the learning of linear function and make a comparative study of the error-remedial effect of students' collaborative learning vs explanatory leaching. We also investigate how to change and advance students' self-diagnosis and treatment of the milton ceptions through the collaborative learning about linear function. The result of the study shows that there are three main kinds of students' misconceptions in algebraic setting like this: (1) linear function misconception in relation with number concept, (2) misconception of the variables, (3) tenacity of specific perspective. Types of misconception in graphical setting are classified into misconception of graph Interpretation and prediction and that of variables as the objects of function. Two different remedies have a distinctive effect on treatment of the students' misconception under the each category. We also find that a misconception can develop into a correct conception as a result of interaction with other students.

• Journal of Educational Research in Mathematics
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• v.8 no.2
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• pp.475-484
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• 1998

In this paper, we give descriptions that the choices made in the Knowledge modelling or representation in Computer Evironments can modify the meaning of this knowledge through a process similar to that of the didactical transpostion. Thus, they are likely to have effects on learning. These problems and phenomena are consequences of general constraints of computer and an algorithms built-in computers. Students may not learn the knowledge intended by teacher. Teacher is always on the alert for the changable mathematical knowledge in computer-based environments. It is an important role of teachers in new teaching and learning environment.