This study aims to reveal fifth grade students' achievement levels in the angles sublearning area and to examine their errors in the subject of angles. The study was designed as a survey, and the study group included a total of 254 fifth grade students attending school in central Nevsehir and in Askale, Erzurum. Data were collected via the "Angle Concept Level Identification Test". Students' achievement levels in the subject of angles were determined by using frequencies and percentages, and qualitative data were analyzed through descriptive and content analysis. The findings showed that the students performed best in naming angles, while merely half or approximately half of them achieved the objectives regarding angle type, measurement and drawing. Also, student errors from most to least frequent could be ordered as follows: angle measurement, angle drawing, reading the angle on the measurement tool, angle definition and angle type. Considering that the concept of angle lies at the foundation of geometry, the findings of the study suggest that building a rich concept of angle is essential to the learning of future mathematical concepts.