• Journal of Educational Research in Mathematics
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• v.27 no.2
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• pp.249-267
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• 2017

The unit of multiplication in the mathematics textbook for third graders deals with two-digit number multiplied by one-digit number. Students tend to perform multiplication without necessarily understanding the principle behind the calculation. Against this background, we designed the unit in a way for students to explore the principle of multiplication with cuisenaire rods and array models. The results of this study showed that most students were able to represent the process of multiplication with both cuisenaire rods and array models and to connect such a process with multiplicative expressions. More importantly, the associative property of multiplication and the distributive property of multiplication over addition were meaningfully used in the process of writing expressions. To be sure, some students at first had difficulties in representing the process of multiplication but overcame such difficulties through the whole-class discussion. This study is expected to suggest implications for how to teach multiplication on the basis of the properties of the operation with appropriate instructional tools.

• Communications of Mathematical Education
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• v.35 no.4
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• pp.505-525
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• 2021

In this study, we investigated how multiplication by 2-digit numbers had been taught in elementary mathematics textbooks of Korea, Japan, Singapore, and USA. As a result of analysis, we found as follows. Korean textbooks do not teach the multiplication by 10 and the multiplication by power of 10, but Japanese, Singapore, and US textbooks explicitly teach related content. In the '×tens' teaching, Japanese and American textbooks teach formally the law of association of multiplication applied in the process of calculating the partial product of multiplication. The standard multiplication algorithm generally followed a standard method of recording partial product result according to the law of distribution, but the differences were confirmed in the multiplication model, the teaching method of the law of distribution, and the notation of the last digit '0'. Based upon these results, we suggested some proposals for improving the multiplication teaching.

• 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.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.1
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• pp.143-168
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• 2019

Along with the significance of algebraic thinking in elementary school, it has been recently emphasized that the properties of number and operations need to be explored in a meaningful way rather than in an implicit way. Given this, the purpose of this study was to analyze how third graders could understand the properties of operations in multiplication after they were taught such properties through a reconstructed unit of multiplication. For this purpose, the students from three classes participated in this study and they completed pre-test and post-test of the properties of operations in multiplication. The results of this study showed that in the post-test most students were able to employ the associative property, commutative property, and distributive property of multiplication in (two digits) × (one digit) and were successful in applying such properties in (two digits) × (two digits). Some students also refined their explanation by generalizing computational properties. This paper closes with some implications on how to teach computational properties in elementary mathematics.

• Journal of Elementary Mathematics Education in Korea
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• v.21 no.1
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• pp.195-214
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• 2017

The standardized algorithm of natural number multiplication simplify the procedure of arithmetic. In the case of multiplication algorithm with regrouping, we write small the carrying number on the multiplicand. But, teachers and students have to make their own way about the case of two digits multipliers, because Korean elementary mathematics textbooks just deal with the case of the one digit multipliers. In this study, we investigated Korean current elementary mathematics textbooks related to multiplication algorithm with regrouping, and analyzed the result of research on the real condition about marking the carrying number. Besides, we reviewed the guidance contents of algorithm of natural number multiplication in Finland's math textbook and literature. By conclusions, we suggest several implications as followed; First, we need some examples of the way to mark the carrying number in teacher's guidance books and textbooks. Second, teachers try for students to feel the good points of the systematic ways to mark the carrying number. Third, teachers understand algorithm of natural number multiplication and the alternative ways about marking the carrying number.

• Education of Primary School Mathematics
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• v.22 no.4
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• pp.281-294
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• 2019

The purpose of this study is to analyze errors and treatment behavior during the course of mathematics learning of academic achievement by applying reflective activities in the second semester of the third year of elementary school. The study participants are students from two classes, 21 from the third-grade S elementary school in Seoul and 20 from the comparative class. In the case of the experiment group, the multiplication unit was reconstructed into a mathematics class that applied reflective activities. They were pre-post-test to examine the changes in students' mathematics performance, and mathematical communication was recorded and analyzed for the focus group to analyze the patterns of learners' error handling in the reflective activities. In addition, they recorded and analyzed students' activities and conversations for error type and error handling. As a result of the study, the student's mathematics achievement was increased using reflective activities. When learning double digit multiplication, the error types varied. It was also confirmed that the reflective activities helped learners reflect on the multiplication algorithm and analyze the error-ridden calculations to reflect on and deal with their errors.

• Communications of Mathematical Education
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• v.19 no.1 s.21
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• pp.1-14
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• 2005

Piaget는 인류가 지식을 구성해 온 방식과 유사한 방식으로 어린이들도 자신들이 학습해야 할 지식을 학습할 수 있다고 가정한다. Kamii는 이 가정을 확인하고자 하는 열망으로 실험교수법을 이용한 수학수업을 실시하였다. 본 고에서는 Kamii가 얻은 결과 중 곱셈에 대한 결과를 발생론적 인식론 입장에서 논의가 이루어 질 것이다. 이 논의는 어린이들이 구성해 가는 지식이 선대인들이 사용하던 지식과 유사하다는 점과 어린이들이 구성해 가는 지식이 완성된 지식의 형태를 갖출 수 있다는 점을 중심으로 이루어진다. 또한, 그 결과로부터 전통적인 수학 교수법에 변화가 있어야 함을 발생론적 인식론을 적용한 수학 수업의 특징과 비교하면서 시사점을 논의하고자 한다.

• School Mathematics
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• v.11 no.4
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• pp.745-771
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• 2009

To acquire the hints of the development of children's multiplication strategies, this study tried to find the differences between the students who learned multiplication and the students who didn't. And we also tried to explore their acquired computational resources. As a result, we confirm that there is a certain direction on the development of children's multiplication strategies according to their grades and the level of acquirement of mathematical knowledge. Moreover, we comprehend that commutative law is an important part of the strategies on two-digit multiplication and that acquisition of the computational resources must precede the learning of multiplication strategies. In the end part, this article proposes a new taxonomy of strategies for multiplication. To support our proposal, we integrated the prior researches with our findings.

• Education of Primary School Mathematics
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• v.22 no.3
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• pp.181-203
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• 2019

Even though the properties of operations in multiplication serve a fundamental basis of conceptual understanding the multiplication with whole numbers for elementary students, there has been lack of research in this field. Given this, the purpose of this study was to analyze instructional methods related to the properties of operations in multiplication (i.e., commutative property of multiplication, associative property of multiplication, distributive property of multiplication over addition) in a series of mathematics textbooks of Korea, Japan, and the US. The overall analysis was conducted in the following two aspects: (a) when and how to deal with the properties of multiplication in three instructional context (i.e., introduction, application, generalization), and (b) what models use to represent the properties of multiplication. The results of this showed that overall similarities in introducing the properties of multiplication .in (one digit) ${\times}$ (one digit) as well as emphasizing the divers representation. However, subtle but meaningful differences were analyzed in applying and generalizing the properties of multiplication. Based on these results, this paper closes with some implications on how to teach the properties of operations in multiplication properties in elementary mathematics.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.55-60
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• 2023

When performing the multiplication m×r=p of two binary numbers m and r on a computer, there is a shift-and-add(SA) method in which no time-consuming multiplication is performed, but only addition and shift-right(SR). SA is a very simple method in which when the value of the multiplier r_i is 0, the result p is only SR with m×0=0, and when r_i is 1, the result p=p+m is performed with m×1=m, and p is SR. In SA, the number of SRs can no longer be shortened, and the improvement part is whether the number of additions is shortened. This paper proposes an SA method to minimize addition based on the fact that setting a smaller number to r when converted to a binary number to be processed by a computer can significantly reduce the number of additions compared to the case of setting a smaller number to r based on the decimals that humans perform. The number of additions to the proposed algorithm was compared for four cases with signs (-,-), (-,+), (+,-), and (+,+) for some numbers in the range [-127,128]. The conclusion obtained from the experiment showed that when determining m and r, it should be determined as a binary number rather than a decimal number.