The purpose of this study is to describe students' critical thinking skills in realistic-based. This research is a qualitative descriptive study. The subjects of this study were students of Elementary School Teacher Education, FKIP, Satya Wacana Christian University in mathematics courses. The data collection technique in this study was a test of students' critical thinking skills. The results of the critical thinking test were analyzed by describing the students' critical thinking skills in the fraction operation. Based on the results of the study, it is known that: 1) students of elementary school teacher candidates need to improve their ability to generalize in teaching addition, subtraction and division arithmetic operations with the same denominator; 2) students need assistance and improvement in their ability to analyze the addition and multiplication count operations with the same denominator; 3)students need assistance and increase their ability to generalize to the addition and subtraction of fractions with different denominators, 4) Students need assistance in improving their ability to analyze multiplication and division counting operations on different denominators.

Online learning is growing along with the development of today's technology. Online learning development will improve the quality of the learning process. The research goal is to improve an online learning portal based on Artificial Intelligence (AI) within the Team-Based Learning (TBL) framework. The benefits of AI in personalizing learning based on how students learn, and even the TBL usage as a learning method, are explored to improve student learning results. The method used in this research is a method for conducting research development. MOODLE as a Learning Management System is being used to expand the online learning portal. In addition, AI technology is developing using algorithms based on collaborative filtering to predict learning styles and evolutionary algorithms to analyze student group growth. There were 262 students from ten elementary schools (SD) in three provinces who participated in this study. The application of the R data analysis program used paired t-test to compare the pre-test and post-test. The findings of this study indicate that AI-based online learning within the TBL framework can significantly improve student learning outcomes.