Analysis of Students' Mathematical Reasoning Abilities Using a Question Development Model Based on 21st-Century Skills

Mathematics is a scientific discipline that contributes a lot to human survival. They will get many things, such as developing reasoning, solving problems, and so on, when facing issues related to mathematics, especially in a century that can be said to be super modern, such as the 21st century, which needs cadres with a high level of reasoning. Mathematical reasoning is one of the competencies that students should have at school. This research aims to determine the level of students' mathematical reasoning abilities in mathematics subjects, especially geometry. The method used in this research is qualitative. The technical analysis in this research is qualitative descriptive data analysis. The techniques used in data collection are test questions and interviews. The research subjects were 16 students, each given the same questions. The research results show that (1) Students in the very-good category are 12.5%, (2) Students in the excellent category are 32.5%, (3) Students in the fair category are 32.5%, (4) Students in the poor category are 22.5%. The analysis results show that the maximum gains are felt by students who often use the question development model. It is hoped that teachers will always encourage their students to take the time to solve mathematical problems, especially those related to geometry, so that their mathematical reasoning abilities develop over time.