Learning materials through saving water

The demands of the 21st century require students to be reliable communicators, creators, critical thinkers, and collaborators in solving problems through student involvement in learning. This research aims to explore the student's mathematical reasoning abilities and problem-solving skills in mathematics using the cost of payments for water use as context. The subject of this research was eight-grade students of SMPN 19 Palembang. This research uses the method of design research with validation studies type which three stages, namely Preparing for the experiment; The design experiment consists of two cycles (Pilot Experiment and Teaching Experiment); and Retrospective analysis. The study results show that learning using receipts of water payments as a medium for saving water can help students develop reasoning and problem-solving skills in mathematics learning. However, students not accustomed to using information obtained from the analysis to solve the given problem. Students tend to provide non-mathematical arguments on each issue that require students to provide discussions about the learning material, especially data presentation.