PENDEKATAN MATEMATIKA REALISTIK PADA PEMBELAJARAN PECAHAN DI SMP

A. Formal Position Number Fraction in Junior High School

Learning mathematics can be started with an introduction the problem which appropriate with the situation (contextual problems). The purpose of learning fraction in school may be mentioned as follows:

1. Solve contextual problems and find the concept of fraction number form contextual problem solved.

2. Understand the concept of fraction number out, explain the relationship between concept and apply the concept of fraction number, flexibly, accurately, efficiently, and appropriately in problem solving.

3. Using the reasoning on the pattern and nature, to manipulate and create generalizations about the fraction number.

4. Communicating the concept and utilize of fraction number.

5. Have respect of usability fraction number in daily activity.

Developing learning fraction number with PMRI approach in Junior High School:
1. Application PMRI

Realistic types that have characteristic bottom to up approach which students develop their own models and then the model is used as the basis for developing formal mathematics. There are two kinds of models that occur that are the model of situation (a model of situation) and for the mathematical model (a model for formal mathematics).

2. Development of mathematical concept through “Iceberg” PMRI

Begin from the real world, then formation scheme, then building knowledge, and the last is formal abstraction.

3. Realistic problems development associated with the fraction number: a discussion for teacher.

a. Fraction and Shape Developing an illustration as a means to find concept related to fractions. Example by using pictures of whole fruits, then split apart into several pieces.

b. Simple Fraction

Example 1 ¾ fraction will be converted into simple fraction, presented in illustration 1 and ¾ parts of apple. So students can get a simple fraction of adding 1 apple (4/4) with ¾ of apple, and the result is 7/4 of an apple.

c. Changing fraction with numerator greater than denominator into mixture fraction

This can be through with device the numerator by the denominator. It will get mixed fraction whose value is the same as ordinary fraction.

d. Comparing Fractions

This can be done to illustrate to be compared on the number line. Or it can also illustrate the distribution of plots.

e. Sorting fraction

To sort the fragments by compared with other fraction.

f. Fractional decimal

This is done by dividing the numerator by the denominator.

g. Percent

Using the first method is by changing the shape percent to ordinary fragtions, then if the fraction is not in its simplest form, change ordinary fraction into simplest fraction first.

h. Add and Subtract fraction

The number of fraction with same denominator, is the sum of the numerator, the numerator divided by the denominator, this applies if the fragments which will be operated in simple fraction form, when the fragments that will have not operated in the simple fractions form, then the task before us simplify first.

i. Reduction of fraction whose denominators equal

The result of reduction of two fractions with same denominator, the numerator is the result of a reduction of fraction of different denominators.

j. Add and subtract fraction mixed

Adding of the mixed fraction can be done by add the natural numbers to natural numbers and fraction number to fraction number.

k. Multiplication of fraction and multiplying fractions by fractions

Multiplication of two fraction is the result times the numerator to nominator devided by product denominator to denominator.