The research
written by Meiliasari was done under design research methodology, conducted
at SDN Percontohan Kompleks IKIP
Jakarta, during the period of May to August 2008. In this study, researcher
concerned about addition and subtraction up to 20, particularly for those in
the low grade of primary school by applying Realistic Mathematics Education. Noticing
to the evidences found, most of children very likely rely on using fingers to
keep track of their counting when doing addition or subtraction at the
beginning. They count all objects one by one that surely will spend a lot of
time, for instance the sum of 3 + 4 = 1, 2, 3, 4, 5, 6, 7. This is assumed as
the simple way to solve addition and subtraction problems. When encountering
the larger numbers, nonetheless, such way is no longer effective.
The researcher,
therefore, conducted this study aiming at developing an instructional program
that helped students to abbreviate strategies of addition and subtraction up to
20 through structures. Structures of numbers, either line or group and
combination model as well, were used as a visualization to enhance students’
thinking process in constructing meaningful and flexible structures such as
using ‘doubles’,’ splitting’, and ‘friends of 10’ which eventually will make
students easier to solve the addition and subtraction problems.
The research was
divided into two parts; part 1 was conducted between May to June, whilst part 2
was running in July. Over those periods, five students who represented the
high, middle, and low achiever groups were picked in the 1st part.
Then, hypothetical learning trajectory will be tested in the learning
experiment in the 2nd part. Lastly, the collected data through
interview and video recording during teaching learning experiment were analyzed
in the retrospective analysis phase.
The learning
activities in this study were generally designed to help students count
effectively. To begin with, the researcher gave students the candy packaging
activity to develop their structure awareness. In this activity, they were
asked to make several arrangements of candy packing –in fives, tens, or other
group structures- with an expectation that they would be able to realize that structuring
helps them do a faster counting. In
addition, working with concrete object (candy) as the characteristic of RME
would make students construct the concept of material easily.
The next
activity was providing the double song and completing the worksheet concerning
about double structure. Then, the 3rd activity was opened with flash card games
forcing students to count quickly how many objects in the card. To do so, they
should recognize the structure well instead of counting objects one by one. For
example, when having the 8 card, some students might see 8 as 10 – 2, whilst other
students use doubling structure 4 + 4 = 8. Through this activity, students
could realize the importance of structure in shortening the counting process.
The following
week, the activity was followed by developing students’ understanding of the
‘friends of 10’. For example, if there are only 7 candies in the box, to make
it 10 how many more need to be put in? The result showed that friends of 10
strategy has allowed students to work faster and easier. Morerever, a trick so
called ‘number pair’ in Indonesian language, pairing the numbers whose same
first letter such as satu-sembilan, dua-delapan, and so on,
worked well on students’ memorizing.
To conclude, a
challenging and interesting instructional program will make students more
motivated and get involved in the activity actively. It is important to make
activity goes along naturally with the real context in students’ surrounding. As
children mostly do in doing addition or subtraction, counting concrete objects
using finger is simple and always works. When working in larger number,
however, students should be encouraged to use flexible and meaningful
strategies such as splitting, doubling, and friend of 10 to make their counting
process easier and more effective.
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