The conceptual understanding of mathematical ability have an important goal in mathematics, gives the sense that the material being taught not just rote, but more so with the understanding that students can better understand the concept of the subject matter. Thus the need to apply an innovative learning that can be applied in mathematics to develop students' mathematical understanding capabilities. The purpose of this study to determine the application of Realistic Mathematics Education approach to improve students' understanding of mathematical concepts in data presentation material. The method used is a quasi-experimental design with non-equevalent control group design. Sampling using purposive sampling technique, where the VA as many as 26 students experimental class and control class VB as many as 26 students. The results of data analysis showed an average of 81.19 posttest experimental class and control class 73.19. As for the test average gain of 0.69 experimental class and control class 0.53. Based on the results of the study concluded that the realistic approach can increase the ability of mathematical understanding, achievement and increase the ability of understanding mathematical concepts that students get a realistic approach better than students who get a contextual approach.

Keywords: Mathematical Concepts Understanding, Realistic Mathematics Education
