Examining Students Proof Writing and Justification Skills in the Context of Sum of Measures of Polygons Interior Angles

The present study aims to examine 8th grade students’ proof writing and justification skills. The research was conducted using the document analysis method. The participants of the study consisted of 16 voluntaries 8th grade students. The participants were determined according to the convenience sampling method. Data were collected with the “geometric proof writing and justification test” prepared by the researchers. The data collection tool was prepared by referring to the 5th, 6th, and 7th grade curricula. “Proof Writing Rubric” and “Justification Rubric” were used to analyze the data. The results of the study showed that 8th grade students’ geometric proof writing and justification skills were at low levels. In addition, it was revealed that their justification skill levels were lower than their proof writing levels.