• Journal of Elementary Mathematics Education in Korea
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• v.19 no.3
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• pp.267-287
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• 2015

In this paper, based on the results of analysis on types and strategies of estimation in measurement in the textbooks according to 2009 revised elementary mathematics curriculum, the following four implications are suggested for curriculum development and textbook development for a later date. First, it is necessary to reconcile curriculum and textbooks in contents for estimation in measurement. In 2009 revised elementary mathematics curriculum, only estimation in length, estimation in capacity, estimation in weight, estimation in angular measure are presented. However, estimation in time and estimation in area are presented in textbooks. Second, it is necessary to introduce various strategies for estimation in measurement. In teacher's manual, three strategies like using referent, chunking, unitizing are illustrated. But in textbooks, such strategies are not illustrated properly. Third, the meaning of the 'estimate' need to be clarified. In textbooks, 'estimate' are used also in other contexts. Fourth, it is necessary to clarify whether or not to deal with estimation in time, estimation in area, and estimation in volume in the school curriculum. In 2009 revised elementary mathematics curriculum, estimation in time, estimation in area, and estimation in volume are not mentioned explicitly.

• Education of Primary School Mathematics
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• v.20 no.1
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• pp.1-18
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• 2017

The purpose of this study is the reorganization of the curriculum on the measurement, a part of the second grade math curriculum, for the improvement of the estimation capability in the elementary school students. Research questions were as follows: (1) how are the estimation capabilities of the students who have taken lessons on the diversified estimation strategies? and (2) how are the mathematical writing capabilities of the students who have taken lessons on the diversified estimation strategies? The study using reconstructed lessons was conducted on 18 second grade students in an elementary school located in Seoul. Results show that the students' estimation capabilities and have improved. They started to use 'about' when writing estimation results, different from writing the accurate measurements. Measurement errors were gradually reduced, ending up with a student who could accurately estimate exactly 1m. In addition, their estimation capabilities in using appropriate estimation strategy and writing skills describing the estimation strategy have improved.

• Journal of Elementary Mathematics Education in Korea
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• v.24 no.1
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• pp.53-87
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• 2020

The purpose of this study was to find a future direction for improving computational estimation instruction through examining the contents of computational estimation included in the 2015 revised elementary school mathematics curriculum and elementary school mathematics textbook and teacher's guide. Through this, several suggestions was made as follow. Firs, it is necessary to emphasize the computational estimation across all grade groups. Second, it is necessary to teach the computational estimation strategies systematically. It was found that it is necessary to reinforce the activities related to computational estimation in the computation related units.

• Journal of Educational Research in Mathematics
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• v.16 no.4
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• pp.273-295
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• 2006

It is the purpose of this study to help computational estimation study to settle down in effective teaching method through analysis how students are understanding computational estimation and what occurs using computational estimation in actual life problem situations. I set 3 cases to accomplish these purposes. (1) How students are understanding computational estimation? (2) How students' computational estimation ability is in applying actual life problem situation? (3) What is students' different attitudes in an actual life problem situation before studying computational estimation and after? To accomplish tile purpose, I chose 6 third grade students and taught 'Computational estimation using actual life problem situation' and analyzed students computational estimation processing. Then I arranged the computational estimation processing in an actual life problem situation and differences between the before and tile after. As a result, I obtained the followings. (1) Need of estimation: Every students could recognize the need of estimation with experiencing an actual life problem situation. (2) Choosing the order of decimals: Students could choose appropriate order of decimals according to an actual life problem situations. (3) Using strategy: They usually use rounding strategy and quite often use special number and compatible number strategy.

• The Mathematical Education
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• v.49 no.3
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• pp.375-387
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• 2010

The focus of this article is the strategies young children use to solve rectangular covering tasks before they have been taught area measurement. seventy nine children from Grade 1 to 4 were observed while they solved various array-based tasks, and their drawing and explanation were collected and analyzed. Children's solution strategies were classified into incomplete covering, inadequate array, array constructed from moveable unit, measurement of one dimension, measurement of two dimension, and calculation. Implications for the learning of area measurement are addressed.

• The Mathematical Education
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• v.48 no.3
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• pp.329-352
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• 2009

The purpose of this study was to investigate the effects of small group cooperative communicative activities on the strategies for estimating measurement. To do this, two research questions were set as follow: First, are there any differences between strategies employed by students in the experimental group and the control group before and after the estimating measurement activities? Second, are there any differences between strategies employed by students in different ability levels(upper, middle, lower) of pre-estimating measurement test in the experimental group? The research results were drawn from the investigation as below: First, the strategical change of before and after the estimating measurement tasks in the experimental group was quite noticeable. Unlike the small strategical change in the control group, small group cooperative communicative learning resulted in a decrease of simple memorization and guessing strategies and an increase of refined strategies such as the standard strategy, clustering, unit load and so on. Second, mathematical communicative activities in a small group cooperative learning showed that the students in the upper level of pre-estimating measurement test used more refined strategies and the students in the lower level used simple memorization and guessing strategy more frequently. And through interaction in small group, students could have chances to recognize error of strategies and to modify and learn strategies. In conclusion, small group cooperative activities allowed students to have chances to communicate mathematically and it is a efficient way of helping students learn estimating measurement strategies.

• School Mathematics
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• v.7 no.4
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• pp.403-425
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• 2005

The study aims to get real picture of primary mathematics education based on RME in the Netherlands focusing on number and operations strand by reflecting and analyzing the documents in relation to the primary school mathematics curriculum. In order to attain these purposes, the present paper describes the core goals for mathematics education, Dutch Pluspunt textbook series for the primary school, and a learning-teaching trajectory by TAL project which are determinants of the Dutch primary school mathematics curriculum. Under these reflections on the documents, it is analyzed what is the characteristics of number and operations strand in the Nether-lands as follows: counting numbers, contextualization, positioning, structuring, progressive algoritmization based on levels, estimation and insightful use of a calculator. Finally, discussing Points for improving our primary mathematics curriculum and textbook series development are described.

• Communications of Mathematical Education
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• v.24 no.1
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• pp.1-27
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• 2010

This study intends to provide implications about sluggish use of calculators in our case by analyzing the math textbook of U.S. Macmillan/McGraw-Hill along with the tendency of paying more attention to math class using technologies. From the results of analysis, this textbook deals with various methods over around 3.3% of all pages, using calculators across all grades from 1st to 6th grade. In particular, it offers guidance into three types such as 'Choose a Computation Method', 'You can also use a calculator.', and 'TECHNOLOGY LINK', while particularly it is impressive in the perspective of using calculators as one of calculation strategies. And case studies of usage in textbooks describe 8 different perspectives as an example-represent; solve problems or equations; develope or demonstrate conceptual understanding; analyze; compute or estimate; describe, explain or justify; choose appropriate calculation method; determine a calculated answer's reasonableness. Reflecting on the fact that we still use calculators in a passive way, there are considerable implications to us.