• Korean Journal of Logic
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• v.17 no.2
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• pp.349-358
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• 2014

Human being has attempted to solve the problem of imperfect knowledge for a long time. In 1982 Pawlak proposed the rough set theory to manipulate the problem in the area of artificial intelligence. The rough set theory has two interesting properties: one is that a rough set is considered as distinct sets according to distinct knowledge bases, and the other is that distinct rough sets are considered as one same set in a certain knowledge base. This leads to a significant philosophical interpretation: a concept (or an event) may be understood as different ones from different perspectives, while different concepts (or events) may be understood as a same one in a certain perspective. This paper claims that such properties of rough set theory produce a mathematical model to support critical realism and theory ladenness of observation in the philosophy of science.

• School Mathematics
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• v.11 no.3
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• pp.431-462
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• 2009

Introduction of logarithm in mathematics textbook in the 7th national curriculum of mathematics is the inverse of exponent. This introduction is happened that students don't know the necessity for learning logarithm and the meaning of logarithm. Students also have solved many problems of logarithm by rote. Therefore, we try to present teaching unit for the logarithm according to the historico-genetic principle. We developed the learning-teaching module of unit for the logarithm according to historico-genetic principle, especially reinvention for real contexts based RME. Loaming-teaching module is carried out as the performance assessment. As a results, We find out that this module helps students understand concepts of logarithm meaningfully Also, mathematical errors of logarithm is revised after the application of learning-teaching module.

• Journal of Educational Research in Mathematics
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• v.18 no.4
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• pp.483-497
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• 2008

This study investigated what kind of informal knowledge is emergent and what role informal knowledge play in process of solving 2-digit by 2-digit multiplication task. The data come from 4 times interviews with a 3th grade student who had not yet received regular school education regarding 2-digit by 2-digit multiplication. And the data involves the student's activity paper, the characteristics of action and the clue of thinking process. Findings from these interviews clarify the child's informal knowledge to modeling strategy, doubling strategy, distributive property, associative property. The child formed informal knowledge to justify and modify her conjecture of the algorithm.

• Communications of Mathematical Education
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• v.13 no.1
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• pp.337-360
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• 2002

그래프 능력을 바탕으로 한 함수의 그래프 표현은 함수 교수 ${\cdot}$ 학습상 중요한 위치를 차지한다. 그러나 부적절한 함수 그래프 과제 교수 ${\cdot}$ 학습 방법은 학생들의 지식 구성, 이해 과정에 영향을 주면서 수학적 오류를 형성하게 하였다. 그러므로 체계적인 오류 분석을 기반으로 한 좋은 교수학적 프로그램을 통해 수학적 오류를 예견하고 학습 과정에서 그것을 잘 처치, 활용하는 것이 효과적인 함수 교수 ${\cdot}$ 학습을 위해 요구된다. 본 연구에서는 지필 환경하에서 함수 그래프 과제를 수행한 학생들에게서 일반적으로 나타나는 수학적 오류를 점검하고, 새로운 교육용 테크놀러지 환경하에서 이러한 수학적 오류가 변화되는 과정을 살펴보고자 하였다. 첫 번째 연구 문제를 위해 고등학생 119명을 대상으로 양적 연구를 실시하였으며, 함수에 대한 개념 이미지로부터의 오류가 가장 많이 나타났음을 확인할 수 있었다. 두 번째 연구문제를 위해 고등학생 2명을 대상으로 사례 연구를 실시하였는데, 그 결과 기존의 수학적 오류가 새로운 교수학적 환경하에서 변화, 극복되는 것을 확인할 수 있었다.

• Journal of the Korean School Mathematics Society
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• v.15 no.4
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• pp.719-745
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• 2012

This research is a study on student's understanding fundamental conception of mathematical curriculum, especially in geometry domain. The goal of researching is to analyze student's wrong conception about that domain and get the mathematical teaching method. We developed various questions of descriptive assessment. Then we set up the term, procedure of research for the understanding student's knowledge of geometry. And we figured out the student's understanding extent through analysing questions of descriptive assessment in geometry. In this research, we concluded that most of students are having difficulty with defining the fundamental conception of mathematics, especially in geometry. Almost all the students defined the fundamental conceptions of mathematics obscurely and sometimes even missed indispensable properties. Prior to this study, we couldn't identify this problem. Here are some suggestions. First, take time to reflect on your previous mathematics method. And then compile some well-selected questions of descriptive assessment that tell us more about student's understanding in geometry.

• Journal of the Korean School Mathematics Society
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• v.16 no.3
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• pp.499-518
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• 2013

The purpose of this study is to examine the preservice secondary mathematics teachers understanding and dimensions of knowledge about definition of irrational numbers and irrational numbers and operations. I adopted a framework consisting of formal dimensions, intuitive numbers, algorithmic dimentions suggested by Tirosh et al.(1998) by adding instrumental dimension for his study. I surveyed 65 preservice secondary mathematics teachers who are in bachelor program and post-bachelor program for teacher certificate by using a questionnaire suggested by Sirotic and Zazkis(2007). The results of this study suggest that 83.1% of the participants gave correct answers in definitions of irrational numbers. 43% of the preservice secondary teachers gave correct answers in adding with irrational numbers. Also 91% of the preservice teachers gave correct answers in multiplying irrational numbers. The preservice teachers appeared to understand irrational numbers and operations at formal dimension. More than half of the preservice teachers gave incorrect answers in adding irrational numbers and a few participants gave incorrect in multiplying irrational numbers. The preservice teachers seemed to understand irrational numbers and operations at intuitive or instrumental dimension. The results also suggest that the preservice secondary mathematics teachers have incorrect understanding about irrational numbers.

• Communications of Mathematical Education
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• v.31 no.2
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• pp.153-166
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• 2017

164 preservice elementary teachers' decision and enactment of their knowledge of fraction multiplication were examined in a context where they were asked to write a story problem for a multiplication problem with two proper fractions. Participants were selected from an entry level course and an exit level course of their teacher preparation program to reveal any differences between the groups as well as any recognizable patterns within each group and overall. Patterns and tendencies in writing story problems were identified and analyzed. Implications of the findings for teaching and teacher education are discussed.

• The Mathematical Education
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• v.60 no.3
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• pp.387-407
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• 2021

The present study was conducted on the assumptions that both progressivist and constructivist education emphasized the subjective knowledge of learners and confronted similar problems when the derived educational principles from the two perspectives were adopted and applied to mathematics research and practice. We argue that progressivism and constructivism should have clarified the meaning, purpose, and direction of 'emphasizing subjective knowledge' in application to the particular educational field. For the issue, we reflected Dewey's theory on the application of past progressivism, and aligned with it, we took a critical view of the educational applications of current constructivism. As a result, first, the meaning of emphasizing subjective knowledge is that each of the students constructs a unique mathematical reality based on his or her experience of situations and cognitive structures, and emphasizes our understanding of this subjective knowledge as researchers/observers. Second, the purpose of emphasizing subjective knowledge is not to emphasize subjective knowledge itself. Rather, it concerns the meaningful learning of objective knowledge: internalization of objective knowledge and objectification of subjective knowledge. Third, the application of the emphasis on subjective knowledge does not specify certain teaching/learning methods as appropriate, but orients us toward a genuine learner-centered reform from below. The introspections, we wish, will provide new momentum for discussion to establish constructivism as a coherent theory in mathematics classrooms.

• The Mathematical Education
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• v.62 no.4
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• pp.515-529
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• 2023

The purpose of this study is to analyze teachers' understanding of the number and operations area of grades 3 to 6 in elementary school mathematics curriculum and to derive implications for improving teachers' understanding of the mathematics curriculum. To this end, elementary school teachers were asked to develop items to evaluate curriculum achievement standards at each grade level, and then the teachers' understanding of the curriculum was examined based on the collected items. As a result of the study, there was a misinterpretation of the achievement standards in approximately 25% of the questions collected. Typically, cases where the content covered by each grade was confused when using textbooks as a standard, or cases where the difference between the content covered by the two achievement standards could not be completely distinguished were found.

• Communications of Mathematical Education
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• v.23 no.3
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• pp.735-760
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• 2009

Most of every teachers' life is occupied with his or her instruction, and a classroom is a laboratory for mutual development between teacher and students also. Namely, a teacher's professionalism can be enhanced by circulations of continual reflection, experiment, verification in the laboratory. Professional development is pursued primarily through teachers' reflective practices, especially instruction practices which is grounded on $Sch\ddot{o}n's$ epistemology of practices. And a thorough penetration about situations or realities and an exact understanding about students that are now being faced are foundations of reflective practices. In this study, at first, we explored the implications of earlier studies for discussing a teacher's practice. We could found two essential consequences through reviewing existing studies about classroom and instructions. One is a calling upon transition of perspectives about instruction, and the other is a suggestion of necessity of a teachers' reflective practices. Subsequently, we will talking about an instance of a middle school mathematics teacher's practices. We observed her instructions for a year. She has created her own practical knowledges through circulation of reflection and practices over the years. In her classroom, there were three mutual interaction structures included in a rich expressive environments. The first one is students' thinking and justifying in their seats. The second is a student's explaining at his or her feet. The last is a student's coming out to solve and explain problem. The main substances of her practical know ledges are creating of interaction structures and facilitating students' spontaneous changes. And the endeavor and experiment for diagnosing trouble and finding alternative when she came across an obstacles are also main elements of her practical knowledges Now, we can interpret her process of creating practical knowledge as a process of self-directed professional development when the fact that reflection and practices are the kernel of a teacher's professional development is taken into account.