Development of Worksheet Based on Realistic Mathematics Education on Ratios to Facilitate Mathematical Reasoning Skills of Phase D Students

This research is based on concerns about the low level of students' mathematical reasoning ability. This study aims to develop a Realistic Mathematics Education (RME) based worksheet on ratio material that is valid and practical to facilitate students' mathematical reasoning skills. This research applies the 4-D development model, consisting of define, design, develop, and disseminate stages. The subjects were 35 eighth grade students of class VIII4 at SMPN 26 Pekanbaru. Data were collected using validation forms and learner response questionnaires to evaluate the validity and practicality of the worksheet. The worksheet is designed with contextual problems, real world situations, and guided activities that encourage students to identify relationships, provide explanations, and draw conclusions related to ratio concepts, thereby facilitating mathematical reasoning skills. The validation results obtained scores of 94.44% for the face aspect, 97.39% for the content aspect, and 95.45% for the construct aspect, with an overall average of 95.76%, categorized as highly valid. The field test involving 35 students obtained a practicality score of 90.54%, categorized as highly practical. Thus, the RME based worksheet is valid and practical to facilitate students' mathematical reasoning skills. Its effectiveness requires further investigation.