This classroom observation had been done in class 5B in elementary school of IBA Palembang on Friday, 23^{rd} September 2011. At that time, the teacher did review* *to the material that had been taught which was determining Least Common Multiple (LCM) and Greatest Common Divisor (GCD) of known numbers. The teacher gave exercise to the students that would be done in group then the teacher also gave exercise that would be done individually.

**B. Goal**

The main goal of this observation is knowing the students ability in solving problem correlated to LCM and GCD.

**C. ****Observation Question**

Observation question of this activity is whether could the students solve problem correlated to LCM and GCD?

**D. Data Description**

The teacher gave exercise to the students and they did in group, which each group consist of four students. The type of exercise given to the students was word problem correlated to LCM and GCD also determined LCM and GCD from two or three known numbers. To solve that problem the students could discuss with their group. The teacher took attention the activity in each group during the discussion. After finishing the exercise, the teacher gave chance to representative of some groups to do the result of their discussion on the white board and presented it in front of the class. Another groups took attention to the students who presented their opinion then they gave response to build the classical discussion that was guided by the teacher. Furthermore, the teacher would give plus point for the students who brave present it in front of the class.

Picture 1. Studentsâ€™ Activity as Discussion in Group

**E. Analysis**

The majority of the students could solve the problem about determine LCM and GCD from two or three known numbers correctly. Each of the students in their group helped each other and they would be able to understand the problem and could solve it. Moreover, according to the observation, there were mistakes done by the students. That mistake correlated to determine the factor of number. But, after discussing it with their friends, the students can solve it correctly. In addition, the problem that happened at the time was there are some students who still confused about the word problem. Finally, they could understand the word problem and could solve it by little bit guidance from the teacher.

Some groups who had finished the exercise gave applause to their group, it was as a sign that they were satisfy with their activity and would give support to others. Then, after all of the groups had finished the exercise, the teacher gave opportunity to each group to present their discussion result in front of the class. During did presentation, almost all of the students took attention to their friend and made a match with their discussion result in group. If there was a same or different answer it would be discussed classically by guidance from the teacher.

Picture 2. The representative of group did exercise on the white board

Picture 3. The representative of group presented their result discussion in front of the class

Furthermore, after did it together in group and discussed it classically, the teacher asked the students whether there were still any students who confused about the material or not. Then, the teacher gave another exercise that had to do individually in certain time. The aim of this activity was knowing the ability of the students individually in solving the problem correlated to LCM and GCD. As a result, there were some students who still could not solve the problem correctly. This case perhaps happened since during discussion session in group they did not do well to understand the problem and they tended to put themselves in comfort zone because there was their friend in their group who had already could solve the problem. That was why they think that they need not to think hard about it. Finally, by giving the individual exercise the teacher would know about the ability of the students individually.

There are a number of positive points which can be taken by applying Realistic Mathematics Education in teaching and learning process of LCM and GCD. Firstly, the motivation and interest to learn mathematics of the students can be improved. Secondly, the activity and bravery of the students can be increased dramatically. Moreover, the students can understand more about concept and the using of LCM and GCD in their daily life.

In addition, doing exercise is also come in handy to improve the students skill to solve the problem. While the final achievement of the students is not the only tool to measure the success of teaching and learning. Otherwise, that more important thing is assessment of the process which is fulfilled by studentsâ€™ activity in doing and thinking to find their understanding by themselves.

Picture 4. One of an Example of Answer Form of the Student

**F. Conclusion**

To sum up, the majority of the students have already understood the concept of LCM and GCD and they can solve the problem correlated to LCM and GCD.