• Journal of Elementary Mathematics Education in Korea
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• v.15 no.2
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• pp.361-383
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• 2011

This study is on teaching about the areas of plane figures through open instruction, which aims to discover the pedagogical meanings and implications in the application of open methods to math classes by running the Math A & B classes regarding the areas of parallelogram, triangle, trapezoid and rhombus for fifth graders of elementary school through open instruction method and analyzing the educational process. This study led to the following results. First, it is most important to choose proper open-end questions for classes on open instruction methods. Teachers should focus on the roles of educational assistants and mediators in the communication among students. Second, teachers need to make lists of anticipated responses from students to lead them to discuss and focus on more valuable methods. Third, it is efficient to provide more individual tutoring sessions for the students of low educational level as the classes on open instruction methods are carried on. Fourth, students sometimes figured out more advanced solutions by justifying their solutions with explanations through discussions in the group sessions and regular classes. Fifth, most of students were found out to be much interested in the process of thinking and figuring out solutions through presentations and questions in classes and find it difficult to describe their thoughts.

• Journal of Science Education
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• v.36 no.2
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• pp.251-262
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• 2012

In this study, we develop 15 learning programs to enhance the variable identification and control abilities for the middle school students and analyze the effect of the programs applied to the class. To increase the learning effect of the variable identification and control abilities, we design the programs so that the students can monitor their thinking processes and also they can evaluate the results from their cognitive activities objectively. We analyze the effect of the programs applied to the class and the results show that the test group, which uses the program, marks higher scores in the variable identification abilities compared to the control group. Also, the test group has the increased level of logic to control the variables. Especially, the effect is higher with the students who do not have any logic to control the variables. From the results, we know that it is possible to improve the variable identification and control abilities of the students through the meta-cognitive learning programs developed by us. Furthermore, the results show that the score of variable control abilities positively correlate with that of meta-cognitive level. It means that the meta-cognitive strategy meaningfully increases the variable control abilities of middle school students.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.127-133
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• 1991

Experiments were conducted to investigate the effect of light shading around the heading stage on grain yield and its components of rice. Early, medium, and late-maturing varieties were trected with the light shading of 50% and 75% from the reduction division stage to 20 days after heading date. Heading date were delayed 2-3 days, whereas the mid -late varieties, Sangpung- byeo, and Bongkwang- byeo were no significantly affected. Culm length was increased and panicle exsersion was reduced as the shading treatments become higher, and the degree of the shading effect was more intensive at 75% of shading. The rate of spikllet degeneration was higher at the secondary rachis branches than the primary rachis branch. The early maturing varieties showed the higher rate of spikelet degeneration. Spikelet number was reduced 12-15, spikelet sterility was increased and ripening rate was declined by the shading treatments. Grain yield was decreased by 30-40% at the shading treatment of 50%, and 50% at the shade treatment of 75%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.30-34
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• 2006

The effect of N-fertilization on yield, milling characteristics and quality of Samcheonbyeo, an early maturing rice variety, was investigated in 2002 to 2004. The study was carried out in the southern alpine area of Un-bong Sub-Station, Honam Agricultural Research Institute. Higher nitrogen levels increased number of panicle and grain per unit area, but lowed ripening rate and decreased 1,000-grain weight. Higher nitrogen levels of up to 90 kg/ha also increased head rice yield. A nitrogen level of 90 kg/ha was found optimal for increasing ripening rate and head rice yield, and rice palatability.

• Archives of design research
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• v.13 no.4
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• pp.195-201
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• 2000

To find out media's function on the various effects in communication, this paper reviews studies that utilize multimedia as a device for conveying information. We discuss multimedia as an integrated symbol system with advantages and also problems in representing information. The cognitive dissimilarity of media could be explained by various attributes of medium that are about physical characteristics and even cognitive actions. With advantages from integrated media and interactivity, multimedia has negative results such as cognitive overload and in that reason systematic approach is needed. This paper shows the factors on media selection and relationship to interface components. To select appropriate media to the needs and situation, it should be considered the user's ${\circled1}$background ${\circled2}$knowledge / frequency of use / expertise, contents ${\circled1}$task nature ${\circled2}$type of knowledge and media ${\circled1}$representation format ${\circled2}$interaction techniques. Varying the media factors and varying the expression factors offers concrete design features.

• Communications of Mathematical Education
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• v.25 no.2
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• pp.381-402
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• 2011

In this paper we study formulae of the triangle's area. We solve problems related with making new formulae of the triangle's area. These formulae is consisted of some elements of triangle, for example side, angle, median, perimeter, radius of circumcircle. We transform formulae $S=\frac{1}{2}acsinB$, $S=\frac{abc}{4R}$, $S=\sqrt{p(p-a)(p-b)(p-c)}$, and make new formulae of the triangle's area. Some formulas are received in the process of Research and Education program in the science high school. We expect that our results will be used in the Research and Education program in the science high school.

• 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.

• Education of Primary School Mathematics
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• v.17 no.3
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• pp.265-276
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• 2014

In this study, we aim to search the utilization plan of primary 3-4 mathematics textbooks for 'Flipped Classroom' practice. In the flipped classroom, students are required to manipulate more rigorous concepts, deal with realistic problems and various activities, and discussions. Researcher analyzed the new mathematics textbooks of primary 3-4 grade that is applied 2014. The criteria of analysis was made of the instructional model for 'Flipped Classroom' that was set up by previous researcher. To practice the flipped classroom, teachers need to design their classes carefully for using selectively many materials of the textbooks to make students participate discussion in the classroom actively and to consider their interests and levels.

• Journal of Educational Research in Mathematics
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• v.19 no.3
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• pp.461-477
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• 2009

In this study, an operational analysis in the context of linear equations is presented. For the analysis, several second-order models concerning students' whole number knowledge and fraction knowledge based on teaching experiment methodology were employed, in addition to our first-order analysis. This ontogenetic analysis begins with students' Explicitly Nested number Sequence (ENS) and proceeds on through various forms of linear equations. This study shows that even in the same representational forms of linear equations, the mathematical knowledge necessary for solving those equations might be different based on the type of coefficients and constants the equation consists of. Therefore, the pedagogical implications are that teachers should be able to differentiate between different types of linear equation problems and propose them appropriately to students by matching the required mathematical knowledge to the students' potential constructs.

• School Mathematics
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• v.16 no.3
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• pp.613-631
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• 2014

The aim of this study was to investigate how the small group activity system influences individual to form concepts of prime number and composite number through activity theory on learning process of mathematically gifted 5th-grade students. Student's worksheets, recorded video, and interview were gathered and transcribed for analyzing data. Process of concept formation and using symbol behavior were used to derive the stage of mathematical concept from students, and the activity system and stage of concept formation process were schematized through analysis of whole class activity system and small group activity system based on activity theory. According to the results of this study, two students who were in different activity groups separated into the state of semi-concept and the stage of complex thinking respectively, and therefore, social context and the activity system had effects on process of concept formation among the students.