The research aim to know the impact of using puzzles in the development of critical thinking with pupils in the fourth grade basic In mathematics, to achieve this goal, The researcher set up (22) Puzzles mystery spread over seven lessons are(Angles, Rectangle and square, Surroundings of rectangle and square, Rectangle and square area, Height and distance, Mass, Capacity), The research sample consisted of (61) male and female students from the School of Abdul Karim Al Ragab, Divided into experimental group numbered (30) pupils have been taught by mathematical puzzles, And a control group numbered (31) pupils have been taught in the traditional way, The study tool is a test of critical thinking and test consisted of (24) items, distributed evenly over the four skills of critical thinking, It follows: The skill of the possibility of the right solution, interpretation Skill.