Abstract :
This research is motivated by the low ability to understand mathematical concepts students, lack of student activity during the learning process, and eroded student knowledge about Riau Malay cultural values. Research carried out at Even semester of 2018/2019 school year which aims to determine the effect Contextual Teaching and Learning (CTL) based learning approaches ethno mathematics about the ability to understand mathematical concepts of Class VII Middle School students State 1 Excitatory. This study took a sample of 46 people purposively sampling, with a population of all eighth grade students of SMP Negeri 1 Rangsang. Research this is a quasi-experimental study (Quasi experiment) consisting of class VII.2 as an experimental class using the Contextual learning approach Teaching and Learning (CTL) based on ethnomatematics and class VII.3 as a class control using conventional learning models. Collection technique The data used is the test technique in the form of pretest and posttest. Test the ability to understand students' mathematical concepts after treatment is analyzed with descriptive analysis and inferential analysis. The results showed differences in the ability to understand mathematical concepts in experimental class students and students control class. This can be seen from the calculation