Fractional division is the highest level of operation in the area of Numbers and Operations in elementary mathematics curriculum. The 2009 revised curriculum prescribes that the second graders must start learning fractional numbers by stages. Students...
Fractional division is the highest level of operation in the area of Numbers and Operations in elementary mathematics curriculum. The 2009 revised curriculum prescribes that the second graders must start learning fractional numbers by stages. Students often find fractional numbers difficult to learn despite substantial efforts for learning how to divide fractions over a long period of time. Fractional division seems to be the most challenging part to teach and learn among the four fundamental arithmetic operations. Textbooks need to facilitate teaching and learning in a way that fractional division will not be limited to simple application of algorithms but become calculations based on students' understanding of concepts. In this context, the present study raised the following questions to comparatively analyze and validate elementary mathematics textbooks for fifth and sixth graders in countries of high pedagogical outcomes and close relevance to Korea in light of organized systems, instructional methods and timings as well as to seek better approaches.
1. How are instructional timings and sequences of fractional division presented in Korea, Japan, the USA, Singapore and Finland?
2. How are instructional methods for fractional division presented in Korea, Japan, the USA, Singapore and Finland?
To explore the study questions abovementioned, Korean math textbooks for fifth and sixth graders as per the 2007 revised curriculum, Japanese 新しい 算數 5-A, 5-B and 6-A from Tokyo Books, the USA Go Math 6 from Houghton Mifflin Harcourt, Singaporean My Pals Are Here! 5A and 6A from Marshall Cavendish Education and Finnish Laskutaito in English 5-2 and 6-2 from WSOY were chosen for analysis.
It should be noted that the instructional timings and sequences of fractional division prescribed in both curriculums and textbooks were analyzed here and that instructional methods were analyzed in terms of 4 categories, viz. unit structures, visual models, sentence-based problems and algorithmic formulation.
Below are the findings concerning the instructional timings and sequences of fractional division.
As for the instructional timings for fractional division, the number of units vary marginally and prove similar in general between countries, which suggests that the instructional timing of fractional division in Korea is appropriate. As for the analysis of instructional sequences, Korea and Singapore teach fractional division by clarifying different kinds of fractional numbers, whereas the instructional sequence in the USA appears to be vague. In common, Korea, Japan, Singapore and Finland teach fractional division first with divisors of natural numbers and then of fractional numbers.
Below are the findings of instructional methods for fractional division. Instructional methods were analyzed in terms of 4 aspects. First, fixed forms of unit structures are found in Korea, Singapore, the US and Finland, whereas unit structures vary with contents in Japan. Japan quantitatively differentiates the content of fractional division in line with levels of difficulties and has many pages reserved for diverse approaches to algorithmic formulation for fractional divisors.
Second, concerning the types of sentence-based problems and materials, Singapore and the US have relatively many sentence-based problems, whilst Japan presents various types of sentence-based problems. Commonly, quotitive division for natural-number divisors and partitive division for fractional divisors are used. Notably, Japan formulates algorithms using multiple problems about determination of unit rates. In view of materials, the US and Singapore adopt real-life issues appropriately intended to help develop a sense of reality.
Third, concerning the analysis of visual models, fraction bars are most frequently used. Singapore and the US mostly use models of fraction bars to induce conceptual understanding from students, whilst Japan uses double vertical lines to visualize the problems related to determining unit rates.
Fourth, algorithmic formulation varies significantly between countries. Korea draws on the reduction to common denominators for divisions between numerators to derive algorithms, whereas Japan presents multiple methods for determining unit rates to have students understand those methods converge on multiplication by reciprocal numbers of divisors. The USA presents the correct concept of a reciprocal number without rationales for multiplication by reciprocals, and guides students to multiply reciprocal numbers of divisors as a way to verify if results are consistent between intuitive division and multiplication by reciprocal numbers. Singapore does not present the meaning of a reciprocal number, while the rest processes are same as the USA to demonstrate that dividing by a divisor corresponds to multiplying by the reciprocal of the divisor in that the result of fraction bars equals to that of multiplying by the reciprocal of the divisor. Lastly, Finland is most distinctive in that no process is presented to make algorithms understood. Instead, algorithms are explicitly presented straightforwardly, while guiding students to learn through exercises.
The following implications may be extracted from the analysis findings. First, sentence-based mathematical problems should be diversified. It is necessary to deal with an array of problems associated with the quotitive and partitive divisions, the determination of unit rates, the inverse of Cartesian products and the inverse of multiplication and to include complex problems that require application of four fundamental arithmetic operations of fractions learned and that help experience various ways of dividing fractions.
Second, visual models should be provided sufficiently. Korean math textbooks present diverse kinds of visual models but still not sufficient quantitatively. Instead, local math textbooks tend to rely more on formul