Abstract

Conjecturing thinking skills are prediction skills obtained from recognizing patterns of mathematical phenomena or real-life problems. Indicators of conjecturing skills, namely: observing cases, organizing cases, finding and predicting patterns, formulating conjectures, validating conjectures, generalizing conjectures, and justifying conjectures. This research aims to develop RBL learning materials with STEM approach. Learning materials that can support the success of learning activities in improving conjecturing skills must be developed by meeting several criteria, namely valid, practical, and effective. The validity score obtained for each device is 3.53 for the student assignment design with a percentage of 88.33%, 3.46 for the student worksheet with a percentage of 86.54%, and 3.5 for the learning outcomes test with a percentage of 87.5%. The average score of the overall learning implementation observation was 3.78 with a percentage of 94.42%. There were 24 completed students or about 80%, the average score percentage of student activity was 94.42%, and 94.47% of students gave positive responses.