• Title/Summary/Keyword: composition and decomposition of numbers

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A review on teaching contents in area of Korean math textbook for first grade - even and odd number, composition and decomposition of numbers, calculation with carrying or with borrowing - (우리나라 초등학교 1학년 수학 교과서 <수와 연산> 영역의 지도 내용 검토 - 짝수.홀수, 수의 합성.분해, 받아올림.받아내림이 있는 계산 -)

  • Lee, Seung;Choi, Kyoung A;Park, Kyo Sik
    • Journal of the Korean School Mathematics Society
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    • v.18 no.1
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    • pp.1-14
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    • 2015
  • In this paper, in order to improve the teaching contents on even and odd number, composition and decomposition of numbers, and (1 digit)+(1 digit) with carrying, (10 and 1 digit)-(1 digit) with borrowing, the corresponding teaching contents in ${\ll}$Math 1-1${\gg}$, ${\ll}$Math 1-2${\gg}$ are critically reviewed. Implications obtained through this review can be summarized as follows. First, the current incomplete definition of even and odd numbers would need to be reconsidered, and the appropriateness of dealing with even and odd numbers in first grade would need to be reconsidered. Second, it is necessary to deal with composition and decomposition of numbers less than 20. That is, it need to be considered to compose (10 and 1 digit) with 10 and (1 digit) and to decompose (10 and 1 digit) into 10 and (1 digit) on the basis of the 10. And the sequence dealing with composition and decomposition of 10 before dealing with composition and decomposition of (10 and 1 digit) need to be considered. And it need to be considered that composing (10 and 1 digit) with (1 digit) and (1 digit) and decomposing (10 and 1 digit) into (1 digit) and (1 digit) are substantially useless. Third, it is necessary to eliminate the logical leap in the calculation process. That is, it need to be considered to use the composing (10 and 1 digit) with 10 and (1 digit) and decomposing (10 and 1 digit) into 10 and (1 digit) on the basis of the 10 to eliminate the leap which can be seen in the explanation of calculating (1 digit)+(1 digit) with carrying, (10 and 1 digit)-(1 digit) with borrowing. And it need to be considered to deal with the vertical format for calculation of (1 digit)+(1 digit) with carrying and (10 and 1 digit)-(1 digit) with borrowing in ${\ll}$Math 1-2${\gg}$, or it need to be considered not to deal with the vertical format for calculation of (1 digit)+(1 digit) with carrying and (10 and 1 digit)-(1 digit) with borrowing in ${\ll}$Math 1-2 workbook${\gg}$ for the consistency.

A Comparative Study between Korea and Japan's First Grade Math Textbooks: centered on Area (우리나라와 일본의 초등학교 1학년 수학 교과서 비교 연구: <수와 연산> 영역을 중심으로)

  • Park, Kyo Sik
    • Journal of the Korean School Mathematics Society
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    • v.17 no.2
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    • pp.235-249
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    • 2014
  • In this paper, teaching contents in area between Korea and Japan's first grade math textbooks are compared. Based on the results of this comparison, implications for improving our grade 1 math textbooks are obtained as follows. Firstly, when describing the configuration of two-digit numbers, it needs to be considered that, after the mathematical description of a concrete material representing two-digit numbers, then it should be processed mathematically. Secondly, with respect to the composition and decomposition of numbers, use of the expression of 'some number and some number' needs to be considered. Thirdly, when reading addition expression and subtraction expression with an equal sign, the way of reading them with terms 'sum' and 'difference' respectively needs to be reconsidered. Fourthly, use of the distinct expression for the supplementing situation and the merging situation respectively and use of the distinct expression for the removing situation and the comparing situation respectively need to be considered. Fifthly, the jump in representing the expression of subtraction of two numbers as the expression of the subtraction or mixed operation of three numbers to explain (some number)-(some number) with borrowing need to be resolved.

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A Comparative Analysis of Introducing Addition and Subtraction in the Korean, Singaporean, American, and Japanese Elementary Textbooks (한국, 싱가포르, 미국, 일본의 초등학교 교과서에 제시된 덧셈과 뺄셈 도입에 대한 비교분석)

  • Pang, JeongSuk;Kim, Leena;Kim, SoHyeon
    • Communications of Mathematical Education
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    • v.36 no.2
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    • pp.229-252
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    • 2022
  • This study analyzed the introduction of addition and subtraction, including the composition and decomposition of numbers in the Korean, Singaporean, American, and Japanese elementary mathematics textbooks. The analytic foci of this study included visual models and their connections with the given problem contexts, the introduction of addition/subtraction or addition/subtraction sentences and their connections with the visual models, and additional activities for students to develop a relational understanding of the equal sign. The results of the analysis demonstrated diverse connections, mainly because the problem contexts, visual models, and the introduction of addition/subtraction or addition/subtraction sentences were implemented differently for each textbook. There were differences among the textbooks in what order of problem contexts were presented. Regarding the use of visual models, two textbooks tended to use one model consistently, whereas the other textbooks used various models depending on the problem contexts. There were subtle but significant differences in introducing addition/subtraction or addition/subtraction sentences. For a relational understanding of the equal sign, all textbooks included activities emphasizing that both sides of the equal sign are equal. Based on the results of this study, this paper closes with several implications related to the problem contexts to introduce addition/subtraction and addition/subtraction sentences as well as the use of visual models, which can serve as a basis for a new unit for the subsequent textbook.

Soil Oribatid Mite (Acari Settling in the Forest Litter in the Different Microenvironments in Mt. Jumbong, Korea

  • Kang, Banghun;Lee, Joon-Ho;Park, Seong-Sik
    • The Korean Journal of Ecology
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    • v.24 no.4
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    • pp.233-237
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    • 2001
  • Changes of the oribatid mite species composition during the litter decomposition was investigated in the north-facing and south-facing slopes with different lower vegetation (annual herbaceous plants in north and perennial Sasa in south) in the altitude 1,000 m of Mt. Jumbong, a nature reserve area in Korea, from August 1994 to September 1995. Total 58 species of oribatid mites were collected. The values of O1son's negative exponential index (k) were -0.56 in the south-facing slope and -0.49 in the north-facing slope, but there was no significant difference between them. The decomposition rate of litter increased rapidly until Oct. 1994, and decreased thereafter. Intensive settlement of the forest litter by oribatid mites was recorded in the autumn periods and it decreased in the next spring and summer. Species diversity index (H'), and species evenness (J') ranged from 1.74 to 2.69, and from 0.57 to 0.93, respectively, and the values were lowest in spring. In the successive periods of growing season, there followed great changes in the structure of species dominance. Heminothrus minor was one of the most dominant species in autumn in the first year when litter were placed, but was never recovered next seasons. In contrast, Platynothrus yamasakii was also dominant in the first autumn, then decreased very low in numbers in next spring and summer, but regained its number in autumn. On the other hand, an increase of the number during these periods was observed by Epidamaeus sp.2. Ceratopia bipilis and Epidamaeus sp.1 were abundant both in the north-and south-facing slopes. Trichogalumna nipponica was only found in the south-facing slope, and Nanhermannia elegantula was only found in the north-facing slope.

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