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The concept of reflection in geometry is quite difficult to teach and so teachers often leave this concept out and move on to the next concept. This happens because the teachers are not capable ofusing creative teaching-learning techniques to promote the understanding of mathematics by students. Conceptually understanding reflections is one of the concepts in Mathematics which students are expected to master. It is likely that students, who understand a concept completely will show comprehension regarding the concept, be able to explain interrelationon concept and able to apply the concept or algorithm flexibly, accurately and efficiently for solving problems. GeoGebra is an IT program that can facilitate learning bystudents in order to lessen their difficulties in studying mathematics. This research was done with the purpose of studying the use of the GeoGebra Software forteaching-learning the concept of Reflection bystudents from grade XI at a Senior High School in Aceh. Based on the results from one-meeting where this software was used, it can be conclude that students’ understanding about Reflections collectively averaged 88 % points, which is in thecategory of very good and individually some students scored 90 to 95 % points which is in the very good or excellent category. Meanwhile, based on the results from the questionnaire, 82.8% of the students were pleased to use the GeoGebra software program for studying the subject of Matrix Transformation or Reflections. However, from the group discussions many students still found it difficult to conclude and note down the characteristics of Reflections which showed a lack of ability to communicate about mathematics.