Investigation of mathematical justification skill levels of middle school 7th grade students

The aim of this study is to determine the level of 7th grade students' justification ability. In addition, it is aimed to determine whether the students' level of reasoning differs according to gender and school types and whether there is a correlational relation between justification and achievement scores. The sample of the study consisted of 254 students, 126 of whom were female and 128 were male. The data consisted of 14 questions including 10 multiple choice questions that measure students 'mathematics achievement and 4 open-ended questions that measure students' ability to justify. The data were obtained from descriptive analysis of the 4 questions in which the reasons for the answers in the Geometry Knowledge Test were requested. In the descriptive analysis, the framework given in Cai (2003) was used. The answers were coded in the form of complete and convincing justification, incomplete justification, false justification and no justification. According to the findings obtained from the research, it was seen that most of the students' solutions were in the wrong justification code in the questions where justification was required. In addition, the solutions encoded in the form of complete and convincing justification were very few. No statistically significant difference was found between the justification levels of student solutions by gender. In other words, the mean score of female students (X = 4,39; S = 1,45) was not significantly different than, the average score of male students (X = 4,13; S = 1,76). Similarly, there was no statistically significant difference between the Geometry Knowledge Test achievement score and justification score (r = ,173; t254 = 2,79; p<0,05). As a result, it is seen that the participants have low and persuasive justification skills, and the students who have high level of achievement according to the statistical results have high ability to justify. As a result, students can reason, draw conclusions and make generalizations through knowledge. Keywords: Geometry of teaching, Justification, Student Achievement