• Journal of Preventive Medicine and Public Health
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• v.32 no.1
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• pp.1-8
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• 1999

Objectives. We conducted this study to obtain basic data of urinary levels of arsenic, cadmium, and zinc in children of Ulsan industrial area and to evaluate the difference in urinary levels of these metals between industrial area and suburban area. Methods. The study subjects were composed of 348(male 182, female 166) school children residing in industrial area and 100(male 50, female 50) school children of suburban area. We analyzed urinary levels of arsenic, cadmium, and zinc using atomic absorption spectrophotometer. Results. The geometric means of urinary level of arsenic, cadmium, and zinc of study participants were 3.69, 0.99, $282.49{\mu}g/l$ respectively. The adjusted geometric means of urinary levels of arsenic, cadmium, and zinc of study participants were 3.92, 1.05, $299.92{\mu}g/g$ creatinine respectively. Conclusions. The children residing in industrial area had the higher urinary levels of arsenic and cadmium than suburban children with statistical significance(p<0.01).

• Journal of the Korean association of regional geographers
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• v.6 no.3
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• pp.83-99
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• 2000

This paper purposes to provide a new perspective for better development of geography texts. For this purpose, we have applied spatial cognition development theory to children's drawings. We have suggested that children's spatial operation ability has three development stages according to their age: topological space, projective space, euclidean space. This study turns out that Piaget and Inhelder's spatial concept development theory is on the right track. However, we make clear that their division according to the age is not always accurate due to children's individual differences. These findings have educational implications as the following: First, it is dubious that most children can understand pictures, pictorial maps and illustrations in the third grader's textbook. Second, current textbooks require pictorial map understanding and drawing to third grade students and map drawing to fourth grade students. However, according to this study, the placement of these tasks are not fit for children's developmental stage because both tasks correspond to euclidean space operation. Therefore, we should remove them from the textbook for children at the age.

• Journal of the Korean School Mathematics Society
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• v.15 no.1
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• pp.183-197
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• 2012

Geometry having long history of mathematics have important role for thinking power and creativity progress in middle school. The regular polygon included in plane geometry was mainly taught convex regular polygon in elementary school and middle school. In this study, we investigated the denotation's extension of regular polygon by mathematical basic knowledge included in school curriculum. For this research, first, school mathematical knowledge about regular polygon was analyzed. And then, basic direction of research was established for inquiry. Second, based on this analysis inductive inquiry activity was performed with research using geometry software(Cabri Geometry II). Through this study the development of enriched learning material and showing the direction of geometry research is expected.

• Journal for History of Mathematics
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• v.20 no.4
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• pp.49-60
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• 2007

In this article, the concept of rigidity of smooth surfaces in the three dimensional Euclidean space which naturally arises in elementary geometry is introduced, and the natural process of the development of rigidity theory for compact surfaces and its generalizations are investigated.

• Education of Primary School Mathematics
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• v.5 no.2
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• pp.111-119
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• 2001

Over the years, the benefits of instructional manipulatives in mathematics education have been verified by classroom practice and educational research. The purpose of this paper is to introduce how the instructional material, specifically, geoboard could be used and integrated in elementary mathematics classroom in order to develop student's mathematical concepts and process in terms of the following areas: (1) Number '||'&'||' Operation : counting, fraction '||'&'||' additio $n_traction/multiplication (2) Geometry : geometric concepts (3) Geometry : symmetry '||'&'||' motion (4) Measurement : area '||'&'||' perimeter (5) Probability '||'&'||' Statistics : table '||'&'||' graph (6) Pattern : finding patterns Further, future study will continue to foster how manipulatives will enhance children's mathematics knowledge and influence on their mathematics performance.

• Education of Primary School Mathematics
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• v.9 no.1 s.17
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• pp.59-64
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• 2005

The purpose of this study is to find out how to use dynamic geometry software such as the Geometer's Sketchpad in elementary math classroom. Fist of all, I reviewed dynamic geometry software's property. Then I considered methods to improve geometry education using this software. Some researchers proposed three types of using the software. But I think using the software and developing instructional materials is different. So, I proposed two types of developing instructional materials using the software and two representative examples.

• Education of Primary School Mathematics
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• v.13 no.2
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• pp.85-97
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• 2010

The purpose of this study is to develop a teaching program in consideration of the geometrical thinking levels of students to make a contribution to teaching figures effectively. To do this, we checked the geometrical thinking levels of fourth-graders, developed a teaching program based on van Hiele's theory, and investigated its effect on their geometrical thinking levels. The teaching program based on van Hiele's theory put emphasis on group member interaction and specific activities through offering various geometrical experiences. It contributed to actualizing activity-centered, student-oriented, inquiry-oriented and inductive instruction instead of sticking to expository, teacher-led and deductive instruction. And it consequently served to improving their geometrical thinking levels, even though some students didn't show any improvement and one student was rather degraded in that regard - but in the former case they made partial progress though there was little marked improvement, and in the latter case she needs to be considered in relation to her affective aspects above all. The findings of the study suggest that individual variances in thinking level should be recognized by teachers. Students who are at a lower level should be given easier tasks, and more challenging tasks should be assigned to those who are at an intermediate level in order for them to have a positive self-concept about mathematics learning and ultimately to foster their thinking levels.

• Education of Primary School Mathematics
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• v.14 no.1
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• pp.13-26
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• 2011

The purpose of this research is to analyze geometrical level and the justification process in the proofs of construction by mathematically gifted elementary students. Justification is one of crucial aspect in geometry learning. However, justification is considered as a difficult domain in geometry due to overemphasizing deductive justification. Therefore, researchers used construction with which the students could reveal their justification processes. We also investigated geometrical thought of the mathematically gifted students based on van Hieles's Theory. We analyzed intellectual of the justification process in geometric construction by the mathematically gifted students. 18 mathematically gifted students showed their justification processes when they were explaining their mathematical reasoning in construction. Also, students used the GSP program in some lessons and at home and tested students' geometric levels using the van Hieles's theory. However, we used pencil and paper worksheets for the analyses. The findings show that the levels of van Hieles's geometric thinking of the most gifted students were on from 2 to 3. In the process of justification, they used cut and paste strategies and also used concrete numbers and recalled the previous learning experience. Most of them did not show original ideas of justification during their proofs. We need to use a more sophisticative tasks and approaches so that we can lead gifted students to produce a more creative thinking.

• Education of Primary School Mathematics
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• v.23 no.1
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• pp.27-44
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• 2020

In this study, we extracted geometrical learning content that is treated similarly in elementary and middle schools, and analyzed the differences between how this study is handled in elementary and middle schools. The analysis tools used in this study were developed by referring to the research results presented by Merrill. Merrill classified the study results into two dimensions: 'performance level' and 'content type', and 'teach station' and 'proposal type' by presenting the contents in the textbook. Based on this classification, this study was conducted. According to the results of the study, nine achievement criteria were extracted as learning factors that were treated similarly in elementary and middle schools. The extracted learning elements were systematically analyzed through analysis tools. The results of this study are expected to provide significant implications for the improvement of mathematics learning and for the improvement of new curricula.

• Communications of Mathematical Education
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• v.24 no.1
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• pp.123-143
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• 2010

The Skeleton Tower problem is an example of a curriculum that integrates algebra and geometry. Finding the number of the cubes in the tower can be approached in more than one way, such as counting arithmetically, drawing geometric diagrams, enumerating various possibilities or rules, or using algebraic equations, which makes the tasks accessible to students with varied prior knowledge and experience. So, it will be a good topic which can be used in the elementary grades if we exclude the method of using algebraic equations. The purpose of this paper is to propose some points which can be considered with attention by gifted children education teachers by analyzing the 4th Skeleton Tower problem solutions made by 3rd and 4th graders in their selection test who applied for the education of gifted children in math at J University for the year of 2010.