The study examined differences in students’ conceptual and procedural knowledge of angles among two grades and gender. Participants were 382 sixth and 376 seventh graders from a metropolitan city in Turkey. Turkish students’ conceptual and procedural knowledge of angles declined from sixth to seventh grade. Gender differences were found for procedural knowledge, but not for conceptual knowledge. Since conceptual and procedural knowledge of angles may have significant influences on the essential subsequent topics in geometry, we need to seriously consider the implications of these gender- and grade-related differences and pay attention particularly to males in Grade 7. The patterns of Turkish students’ conceptual and procedural angle knowledge were discussed, and educational implications were offered
