The development of RBL-stem learning materials to improve students’ combinatorial thinking skills in solving b-coloring problems for companion farming

Research Based Learning can be packaged with STEM approach. In a RBL, students will find a problem that requires a solution, problem solving skills are very important in learning. One of these mathematical thinking skills is combinatorial thinking skills. b-coloring is one of the concepts of graph theory. b-Coloring is widely applied in various fields, one of which we can apply to companion farming precision agriculture The development of RBL-STEM learning tools to improve students' combinatorial thinking skills in this research meet the criteria of valid, practical, and effective. The validity scores was 3.87. The observation results of learning implementation were 3.83 with a percentage of 95.75%, and student responses were 96.5% positive so that they met practical criteria. Based on the test results, researchers found that 97.5% of students were complete so that they met the effective criteria. Quantitative analysis involves processing pretest and posttest data, where normality test and paired sample t-test are conducted. Based on the normality test, it can be concluded that the pretest and posttest scores have a normal distribution, because the p-value is greater than 0.05, namely 0.053 and 0.059. Furthermore, a paired sample t-test was conducted which showed a p-value of 0.000. These results show that there is a significant increase in students' combinatorial thinking skills after participating in the learning.