This study aims to describe the understanding of fifth-grade students' science concepts at SDN 127 Bila, Amali District, Bone Regency, on the topic of changes in state of matter. The research focuses on students' understanding of the concept of changes in state of matter, the difficulties encountered, and the use of learning media to support understanding. The research method used was descriptive qualitative, with data collection techniques through interviews, and tests. The results showed that most students were able to understand basic concepts of changes in state of matter, such as melting, freezing, and evaporation, through concrete examples from everyday life. However, students still had difficulty distinguishing more complex concepts, such as sublimation and evaporation, due to their lack of direct encounters with examples. Furthermore, the use of concrete media, such as ice cubes, candles, and camphor, has been shown to help students understand the material more easily, although its effectiveness still needs to be improved through a variety of media and learning methods. Based on these findings, it is recommended that teachers more frequently present simple experiments and media visualizations to strengthen student understanding, while further research can examine the effectiveness of experiment-based science learning strategies in improving understanding of more complex concepts.