The Developing Realistic Mathematics Education of Learning Cylinder in Junior High School Class IX

Introduction
Mathematics is viewed as an activity, a way of working.  Learning mathematics means doing mathematics, of which solving everyday life problem is an essential part.
The aims of teaching learning of mathematics in Junior High School covers:
1.    To understand the concepts of mathematics, to explain the relationships among them and to apply them to solve the problems accurately and efficiently.
2.    To develop thinking skills to learn patterns and characteristics of mathematics, to manipulate them in order to generalize, to proof and to explain ideas and mathematics propositions.
3.    To develop problems solving skills which covers understanding the problems, outlining mathematical models, solving them and estimating the outcomes.
4.    To communicate mathematics ideas using symbols, tables, diagrams and other media.
5.    To develop appreciations of the uses of mathematics in daily lifes, curiosity, consideration, and willingness to learn mathematics as well as tough and self-confidence.
Realistic mathematics education is one effective way to teach mathematics is abstract. In learning activities, teachers teach the material to relate it to everyday life. A lot can be connected between mathematics with everyday life.
Realistic mathematics education is divided into four sections relating to each other, namely:
1.    Concrete Mathematics
Concrete mathematics is the introduction of a material by connecting it with things that exist in everyday life. Here students are encouraged to know first what is the basis of the material. For example, in teaching the tube, students can be directed first at a building in the shape of a tube. For example, the tower in Pisa, the students know the shape of the tower of Pisa then students will also have the idea that a picture of a tube is a building shaped like a tower of Pisa.
2.    Concrete Model of Mathematics
Concrete models of mathematics is a picture that can represent the original. Once students know the original, then invited the students to be able to describe it in the form of a picture that represents the original.
3.    Formal Model of Mathematics
Here the authors also use the image above to explain how the shape of a tube if drawn. From the image, then students are asked to identify how the properties of the tube. Then students can make using a paper tube.
4.    Formal Mathematics
Mathematics builds on formal logic.It has been written with symbol mathematics such as number and symbol. In the book "Mathematics for Junior High School Class IX" (Marsigit, 2009), the author invites students to find a formula for the volume and surface area of the cylinder tube.
Conclusion
Realistic mathematics education can be accomplished if a teacher is able to understand and connect mathematics to the material things that exist in everyday life. Teachers need to know about concrete mathematics, concrete models of mathematics, formal models of mathematics, and formal mathematics.
References :
Marsigit . 2009.Mathematics For Junior High School Year 3. Jakarta: Yudhistira
http://staff.uny.ac.id/sites/default/files/penelitian/Marsigit,%20Dr.,%20M.A./Marsigit_Paper_APEC%20Conferen_Chiang%20Mai_Thailand_November%202010.pdf