This chapter aims to provide a comprehensive understanding of how LEGO can be utilized as an educational and playful tool to foster active learning through hands-on problem-solving and reflective thinking. In prior studies, playful learning has been recognized to be an effective strategy for engaging students in complex and abstract topics. However, the focus was mainly on the students’ views, and less attention was paid to teachers’ perspectives. This chapter aims to fill this gap by examining teachers’ views and experiences with LEGO-based courses on applying problem-solving and reflective activities, all essential skills for engineering education and twenty-first-century skills. In total, 17 participants discussed their experiences with LEGO-based learning during semi-structured interviews, providing rich examples in two types of LEGO on problem-solving, with a case in design for recycling, and on reflective practice with a case on organizational teamwork and collaboration. These examples also highlight how this approach could be used in sustainability and engineering education to foster a dynamic and interactive learning environment, indicating several benefits of playful LEGO-based learning, such as student engagement, innovative approach to learning, context adaptability, reflective thinking, and professional growth, among others. In addition, data collection revealed specific problem-solving strategies and a reflection process with LEGO. The study is concluded with design suggestions for educators who want to develop or adopt formal and non-formal educational activities based on playful learning and LEGO.