This study aims to find out the politeness strategies used by the teachers and how the politeness affects to the student's compliance. The focus is on directive and expressive speech acts. The subjects of this study were two teachers and the students of class II-A and II-B at SD 024184 Binjai Timur Binjai. The data was gathered by video audio recording the teachers' utterances and the students' compliances to the teacher, in order to find the teacher's politeness principles and the students' compliances to the teachers' utterances. In the data analysis, it is found that 1) the teachers used four maxims in their communication to the students. They are tact maxim, generosity maxim, approbation maxim and agreement maxim. It is not found that the teachers used modesty maxim and sympathy maxim. 2) The teachers were dominantly used tact maxim in their directive speech acts to the students. 3) Children pragmatic competence and positive emotions were the factors that affected the students' compliances to the teachers' politeness utterances.