This research is motivated by the low ability of understanding vocational students. This study will examine the improvement of students' mathematical understanding ability using discovery learning with the usual approach. The method used is the experimental method with the design of pretest-posttest control groups, namely designs that involve at least two groups and random sampling of classes. At the beginning and end of the study both classes are given a test. The population in this sample are all vocational high school students whose characteristics have low mathematical comprehension ability. Of all vocational schools randomly selected and selected Cimahi IT Development Vocational Schools representing the characteristics of the population. The sample was chosen randomly, where class XI RPL C became the experimental class, and class XI TEI B became the control class. Collecting data in this study using a description test that has been tested beforehand, then the scores of students' mathematical comprehension ability were analyzed with descriptive and inferential statistics using two average difference tests. Based on the results of the study, both data analysis and hypothesis testing, with α = 0.05, it was found that the improvement of students' mathematical understanding ability using discovery learning was better than students who used the usual approach, as well as the achievement of better understanding abilities. Keywords:  understanding, discovery learning.

The low skill of students' mathematical understanding can affect the quality of students' learning which has an impact on the low achievement of students' in schools. One effort to improve the skill of understanding is by choosing and applying the model of learning that can enable students' eagerness to learn, namely cooperative learning model which can be used as an alternative learning model. Objectives to be gained in this study is to determine whether there is difference in the skill of mathematical understanding of junior high school students which use contextual approach setting cooperative learning model NHT type with STAD type on the subject of bangun ruang sisi datar. The method used in this research is subject experiments to students of SMP class VIII which is divided into two experimental groups, namely NHT type and STAD type. Teachers can develop cooperative learning model because it can improve students' learning outcomes. Teachers should experiment with learning methods more for the sake of the most appropriate and varied models selection. Key words: Mathematical understanding, Cooperative Learning, NHT, STAD