Abstrak
<p>This research is based on the fact that the understanding of mathematical concepts of the seventh grade students of SMPN 1 Talamau is lacking. It is disebapkan by the process of learning mathematics that occurred has not involved students optimally in understanding the mathematical concepts. Efforts that can be done is to apply the model of learning Numbered Heads Together (NHT) by using Mind Mapping. The purpose of this study is to find out whether the understanding of mathematical concepts of grade VII students of SMPN 1 Talamau using the model of learning Numbered Heads Together (NHT) using Mind Mapping is better than understanding the mathematical concepts of students using conventional learning. This type of research is quasi-experimental research. Sampling is done using Random Sampling technique so that the selected as experimental class is VIIc class student and as control class is student of class VIIa. Data analysis is done by using t test with level α = 0,05 obtained titung = 1,74> ttabel = 1,671 mean hypothesis accepted. So it can be concluded that the understanding of students' mathematical concept using the model of learning Numbered Heads Together (NHT) using Mind Mapping is better than the understanding of mathematical concepts of students using conventional learning model.</p>