# Teaching and Learning The concept of Adding and Subtracting of Whole Numbers up to Nine Hundreds Using RME Approach in Indonesian Primary School

A.    INTRODUCTION

This observation report explains about the process of teaching and learning adding and subtracting up to nine hundreds without saving at SD Negeri 98 Palembang, South Sumatera, Indonesia by using Realistic Mathematics Education Approach with stone and arrow cards as a model of and model for respectively. This activity involved 35 pupils.

In this observation, I was a teacher in the classroom. The teaching and learning activities ran about 60 minutes. When I was teaching, I also did documentation and guided the students to follow the instruction. In this meeting, I introduced the concept of addition up to nine hundreds to the students through telling the story titled “Perjalanan Si Bolang”.

B.     DISCUSSION FINDINGS

I conducted my observation in SD Negeri 98 Palembang, a public primary school located at K.H.A. Azhari street, 14 Ulu, Palembang on the 8th of October, 2011. It is one of the public primary schools in Palembang that has been applying PMRI in the classroom.

When I met with Mrs. Ningcik, as she called, she said that the students at grade III start their lesson in the noon, around 1.20 p.m. Presently, the topic for mathematics subject is adding up to one thousands. But than, she suggested me to start with adding without saving. By discussion with her, either by phone or message, I also told her that I am planning to use story as a context in teaching the concept of adding up to one thousands and she agreed with it.

C.    GOAL OF OBSERVATION

The goal of this research is to make students understand the concept adding up to nine hundreds without saving by using Realistic Mathematics Education Approach.

D.    OBSERVATION FINDINGS

The teaching and learning process started around 1.30 p.m. and the teacher checked the students’ attendance and prepared them for learning. In this meeting, I was a teacher in the classroom. I began by diving the students into small groups consist of 4 members. Then, I explained about what I am going to do in this meeting. I showed the stones to the students and explained to them that they are three kinds of them differentiated by the colors. The stones with green color represent hundreds, the stones with red color represent tens, and the stones with yellow color represent ones.

Figure 1. Three kinds of stones

Before telling the story as a context in teaching the concept of adding up to nine hundreds, I checked the students’ understanding about place value. This concept is really important in order to understand the topic of adding up to nine hundreds. I checked their understanding by using game. I asked several students to take the stones in the box randomly. The, he or she has to explain to the others what numbers that the stones represent and what the reason she or he said like that. One of students, syarif, came to the in front of the class and did the game. He took several kinds of stones and tried to answer what number that represented by those stones. He struggled for the first time. But, after I gave the example and explanation, he then came to the answer.

Figure 2. Syarif is taking the stones from the box

After doing this game, I gave the three kinds of stones to the students in the small group. Every group take nine green stones, nine red stones and nine yellow stones. I also explained the rule of the game in order to follow the story as a context. I explained to them that every time I said numbers throughout the story, they have to arrange the stones that represent those numbers. Then, I started read the story titled Perjalanan Si Bolang.

Figure 3. The student is trying to arrange the stones that represent the numbers in the story

In the story, I began with the numbers consist of tens and ones such as 12 and 15 in order to guide the students to add numbers from the easiest to the hardest ones. Throughout this story, the numbers are going harder than before such as 315 and 153. They have to add those numbers by using the stones. Because the context is a story, the students are not only learned about addition, but also subtraction in the same time. Furthermore, they learned other words to represent addition and subtraction such as “go up” (naik) and “go down” (turun). When I said that the passengers are go up to the Trans Musi Bus, they directly think that it must be addition. Likewise, when I said the passengers are go down from Trans Musi Bus, they directly subtract the numbers.

Figure 4. Trans Musi Bus as a context

After reading the story, I gave the students a realistic problem written in the paper. The problem is really related to the topic. When facing the problem, the students were struggling to solve it. After discussion with them, I found that most of them are got confused with the problem. They did not understand about what the problem really is. They did not get the meaning of word “memperoleh” and “memberi”. So, I explained about it to them. Then, most of them can solve the problem by using formal mathematical counting.

Figure 5. Students solution

E. ICEBERG

Figure 6. Iceberg of adding and subtracting up to nine hundreds

In this observation, unfortunately, I did not use arrow cards as a model for in teaching and learning the concept of adding and subtracting up to nine hundreds due to the lack of time. But, actually, I have prepared for it.

F.    CONCLUSION

In conclusion, I have already known that teaching and learning of the concept of adding and subtracting up to nine hundreds is really interesting if we use Realistic Mathematics Education Approach. Most of the students in the classroom are really active and they feel happy learn mathematics in this way. Besides this fact, there are still some problems that I am going to solve in the next instructional design such as the way I inform the students about the problem, the way I manage the classroom and take a lot of discussion with the teachers in the school.