For future generations to be prepared to deal with global concerns in a world that is becoming more complex and interdependent, early critical thinking and sustainability awareness development are essential. This study demonstrated a Thinking Skill Learning Strategy in education for sustainable development by looking at how 9-year-old primary school pupils utilized their knowledge through a cooperative Mystery assignment. The Mystery Learning Strategy promoted critical thinking, social interaction, and personal growth within a sociocultural framework, supporting pluralistic and holistic educational approaches. Based on participant observations and motivated by lesson study concepts, the results showed that although the Mystery technique is dynamic and captivating, it needs appropriate facilitation to be successful. The study showed that pupils were encouraged to collaborate and think critically.