This type of research is development research that refers to the theory of Borg and Gall. The population of this study was all fifth grade students in SD Negeri Gugus I, Rajabasa Subdistrict and a sample of 51 students obtained by purpose sampling technique were students of class V B of SDN 1 Rajabasa as Experimental Classes and students of class V B SDN 3 Rajabasa as a control class. Data collection techniques use test results of learning and observation. The feasibility of the instrument is theoretically based on expert judgment with an average of 90.09 very good categories. While the feasibility of the instrument empirically based on the analysis 20 essay questions are worthy and quality from the results of the test of validity, reliability, different power, and level of difficulty. Mathematical textbooks based on realistic approaches are also effective. This can be seen from the average value of students in the experimental class using a realistic textbook based on mathematical approaches that is 74.29 higher than the average value of students in the control class who do not use mathematical textbooks based on realistic approaches, namely 59.47 with the normalized Gain value of 0.38 with the "medium" category.